Glossary S - Yenra

49 definitions in this view. Search all 509 terms by name, phrase or topic.

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Transport & aerospaceSAE viscosity grade

A classification of an oil's flow behavior under specified temperature conditions, written as a complete grade such as 0W-20. The viscosity grade is one part of selecting engine oil. Match it together with the required performance category and any manufacturer specification in the manual for the exact vehicle and engine.

Guide: Motor Oil: Match the Specification to Your Engine

Reference: API: motor-oil viscosity grades and performance markings (PDF)

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Historical names & systemsSA (GPS)

Selective Availability, intentional degradation formerly applied to the publicly available GPS signal. The U.S. government discontinued its use in May 2000.

Reference: GPS.gov: Selective Availability

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Audio & videoSample rate

The number of samples taken or represented per second for a signal, expressed in hertz. In audio, 48 kHz means 48,000 samples per second per channel. Sample rate helps determine the frequency range that can be represented; bit depth and the encoded bit rate describe other aspects of the data.

Guide: Speech codecs: why phone-call quality changes

Reference: RFC 4867: sampling frequencies and encoded speech

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Computers & specificationsSATA

Serial ATA: an interface family for connecting storage devices such as hard drives and SSDs to a host. SATA support is a compatibility requirement for the drive, connection and enclosure. M.2 describes a module format that can carry different interfaces, so check whether an M.2 product uses SATA or PCIe/NVMe.

Guide: Toshiba XG5-P Client NVMe SSD: Compatibility and Upgrade Checks

Reference: SATA-IO: the SATA ecosystem

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Food & cookingSauté

To cook food quickly in a hot, shallow pan with a small amount of fat, commonly using small or thin pieces. Give the food enough space for contact with the pan and for moisture to escape. Adjust heat to the ingredients and cookware; gentle sweating instead aims to soften aromatics with little browning.

Guide: Sautéing: Heat, Pan Space and Three Useful Methods

Reference: Escoffier teaching text: sautéing and pan-frying (PDF)

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Business & organizationsSBIR

Small Business Innovation Research, a U.S. program supporting small-business research and development with commercialization potential. Eligibility and open opportunities are set by current program and agency rules.

Reference: SBIR and STTR programs

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Computers & specificationsScalability

The ability of a system to accommodate a larger workload or deployment. A useful claim identifies what grows, which resources must be added and how performance changes.

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Web & documentsSchema validation

Checking a document against a defined set of structural and data rules, such as an XML schema. It can catch invalid structure or values; authorization, safe parsing and application-level checks address other requirements.

Read the guide: Web Service Security: Access, XML Parsing, and Resource Limits

Reference: OWASP: web-service security

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Transport & aerospaceScramjet

Supersonic-combustion ramjet: an air-breathing engine in which airflow remains supersonic through the combustion region. It is a particular engine concept within high-speed propulsion.

Related coverage: Ramjet definition

Reference: NASA: ramjet and scramjet propulsion

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AccessibilityScreen reader

Assistive software that presents digital content and interface information through synthesized speech or refreshable braille. It lets users navigate structures such as headings, links and form controls. Meaningful markup, labels and reading order help it communicate the page; converting a picture of text with OCR supplies only one part of that structure.

Guide: Accessible PDFs with Adobe Acrobat: Create, Check and Repair

Reference: W3C: assistive tools and techniques

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Historical names & systemsSDC (SanDisk)

Service Delivery Card, SanDisk's product name for an operator-oriented storage-card system. Its service and device claims belong to that implementation and period.

Related coverage: Service delivery card

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Web & documentsSDK

Software development kit: tools, libraries, documentation and examples provided to help developers build for a platform or service. Compatibility depends on the SDK version and its target environment.

Related coverage: On2 DirectShow VP8 SDK

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Rocks & EarthSedimentary rock

Rock formed by the accumulation and consolidation of sediment or by material precipitating from solution. Layers, grain sizes and fossils can provide evidence about its formation environment.

Read the guide: Rocks and Minerals: A Guide to Observing and Understanding Them

Reference: National Park Service: rocks

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Security & privacySegmentation (network security)

Dividing a network into areas with controlled communication between them. Enforced boundaries can limit how far an intrusion spreads; the result depends on the actual access rules and paths between segments.

Read the guide: Anti Virus and Malware: Protection, Recovery, and Outbreak Lessons

Reference: CISA: ransomware guide

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Rocks & EarthSeismic waves

Waves of energy traveling through the Earth or along its surface, generated by earthquakes and other sources. Differences in wave speed and behavior help scientists infer properties of the Earth's interior.

Read the guide: What Rocks Reveal About Earth's Interior

Reference: USGS: inside the Earth

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AccessibilitySemantic HTML

Using HTML elements according to the meaning and role of the content they represent, such as headings for section titles, buttons for actions and tables for tabular data. Appropriate native structure helps browsers and assistive technology interpret a page. Preserve a coherent reading order and verify actual interaction behavior alongside the markup.

Guide: FrontPage Accessibility: Modernize an Older Website

Reference: W3C: meaningful page structure

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Science & measurementSensor response time

How long a sensor takes to respond to a specified change in its input under stated conditions. For a step-response specification, this can be the time until the indication settles within stated limits around its final value. The logger's sampling interval is a separate setting: frequent readings of a slow probe can still miss a brief event.

Guide: Data Loggers: Plan a Measurement You Can Trust

Reference: JCGM VIM: step response time

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Computers & specificationsSEPIC

Single-ended primary-inductor converter: a DC-to-DC converter topology that can produce an output voltage above or below its input voltage. Component ratings and the specific circuit determine usable operation.

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Rocks & EarthSequential color scheme

A set of colors arranged to communicate an ordered progression, such as low to high values on a map. A light-to-dark progression is common; hue can change as well. Choose readable steps that preserve the order, and define the numeric class boundaries separately so each color has a clear meaning in the legend.

Guide: Map Colors with ColorBrewer: Choose, Classify, and Check

Reference: ColorBrewer: sequential, diverging and qualitative color schemes

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Web & documentsSGML

Standard Generalized Markup Language: a standard for defining markup languages for structured documents. It is part of the historical background of HTML and XML; modern HTML has its own parsing rules.

Read the guide: SGML, XML, and HTML: Understanding Structured Documents

Reference: W3C introduction to SGML

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Tools & workshopShank (tool)

The part of a bit or cutting tool that fits into the tool holder, such as a drill chuck. Its diameter and shape determine the required holding interface. The cutting diameter can differ from the shank diameter, so check both, together with the tool's rated capacity and the accessory's intended operation.

Guide: Drill Bits: Match the Material, Hole and Drill

Reference: Bosch: drill shank shapes and tool compatibility · Bosch: straight and reduced-shank bits (PDF)

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PhotographyShutter speed

The duration of an exposure, usually expressed in seconds or fractions of a second. A shorter exposure gathers less light at the same aperture and can reduce motion blur; a longer exposure allows more light and more movement. Rolling shutter describes how the image is read out, a separate timing property.

Guide: Better Phone Photography: Override Auto Exposure on iPhone and Android

Reference: Nikon: exposure and shutter speed

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PhotographySidecar file

A separate file stored alongside an image to hold information such as metadata or editing instructions. Keeping the image and its associated sidecar together helps preserve edits when moving or backing up a photo collection.

Read the guide: Photo Storage: Organize, Back Up and Recover Your Pictures

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NetworksSignal-to-noise ratio

The ratio of signal power to noise power for a stated measurement, commonly abbreviated SNR and expressed in decibels. When both powers are measured in dBm under comparable conditions, subtract the noise reading from the signal reading to obtain SNR in dB. Record the measurement conditions and available noise evidence before using it to assess a wireless link.

Guide: Wi-Fi Site Survey: Map Coverage and Validate Real Tasks

Reference: Cisco Meraki: signal-to-noise ratio and wireless measurements

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Art & colorSilhouette

A shape read mainly through its outer contour, often as a dark or flat area against a contrasting background. In an artwork, silhouettes can clarify figures and organize relationships even when interior detail is limited.

Read the guide: How to Look at Seurat’s La Grande Jatte

Reference: Art Institute of Chicago: La Grande Jatte

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Historical names & systemsSISTM

Sport Integration System, H2O Audio's name for an accessory-mounting system in period iPod coverage. Its fit and intended uses belong to the documented accessory models.

Related coverage: Sports music system

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Computers & specificationsSnapshot (storage)

A retained view of stored data at a particular point in time, useful for retrieving an earlier file version or state. Its recovery value depends on the system, retention and access controls. A snapshot kept only on the same failed or inaccessible storage can share that storage's loss, so assess independent backup separately.

Guide: Storage Mirroring and Replication: Failure Scenarios and Recovery Tests

Reference: Microsoft: file-share snapshots and their protection limits

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Computers & specificationsSoC

System on a chip: an integrated circuit combining several major system functions, such as processing and interfaces. The functions included vary with the intended device.

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Security & privacySoftware patch

A software change supplied to correct a defect, vulnerability or other identified problem. A security patch addresses a security issue; software updates can also add features. Confirm that the fix applies to the installed product and version, then verify installation and any required restart before considering the issue addressed.

Guide: Zotob: What the Patch-to-Outbreak Timeline Teaches

Reference: NIST: patch

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Historical names & systemsSONET

Synchronous Optical Network, a standardized optical transport system associated with North American telecommunications. Interpreting an inherited circuit requires its line rate, payload, timing and handoff details.

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Rocks & EarthSpatial resolution (imagery)

The spatial detail an image can distinguish. In Earth imagery it is often described using ground pixel spacing, but sharpness, blur and noise also affect what can be resolved. Compare the sensor and processed product as well as pixel size; closely spaced samples alone do not guarantee that small features are distinguishable.

Guide: Yangtze River: From Drainage Basin to Sediment Plume

Reference: USGS: spatial data quality and image sharpness

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Audio & videoSpeaker impedance

The electrical opposition a speaker presents to an amplifier’s alternating output, expressed in ohms. It varies with frequency; the nominal rating summarizes a changing load. Use the speaker and amplifier specifications together when checking compatibility, including relevant minimum-impedance limits and permitted speaker arrangements.

Guide: Digital Audio Amplifiers: Class D, Power, and Speaker Matching

Reference: Yamaha: speaker impedance and nominal ratings

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Audio & videoSpeaker sensitivity

A measure of a speaker’s sound-pressure output at a stated distance for a specified input, commonly reported in decibels at one meter. Compare the reference conditions: ratings based on one watt and on 2.83 volts can differ with impedance. Sensitivity helps estimate output requirements; it is separate from maximum power handling.

Guide: Digital Audio Amplifiers: Class D, Power, and Speaker Matching

Reference: Yamaha: sensitivity and amplifier power ratings

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Rocks & EarthSpectral band

A selected range of wavelengths measured by an imaging sensor or admitted by a filter. Different bands can reveal different properties of vegetation, water, rock or emitted heat. Check the sensor's wavelength ranges before comparing band numbers, and keep the measured band separate from the visible color assigned to it in a displayed image.

Guide: Earth Imaging: Choose and Compare Satellite and Aerial Images

Reference: NASA Landsat: spectral bands and their applications

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Science & measurementSpectrum (light)

A representation of light separated by wavelength, frequency or photon energy. An astronomical spectrum shows how a measured quantity, such as brightness or the fraction of starlight blocked, changes across that range. Its features can help investigate composition or motion. Read the axes, units and uncertainty before interpreting a peak or dip.

Guide: James Webb Space Telescope: How to Read Its Images and Spectra

Reference: NASA Webb: spectroscopy and scientific instruments

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Security & privacySPF

Sender Policy Framework: an email mechanism that lets a domain publish which hosts may use its name in the SMTP envelope sender or HELO identity. A receiving server checks the sending host against that policy. The identity checked can differ from the visible From address; use DMARC alignment to connect authentication to that address’s domain.

Guide: Email Sender Authentication: SPF, DKIM, DMARC, and Their Limits

Reference: RFC 7208: Sender Policy Framework

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Computers & specificationsSPP

Serial Port Profile: a Bluetooth Classic profile that uses RFCOMM to emulate a serial cable connection between devices. A compatible host may expose this as a virtual serial port. Check the adapter’s role and host support; a Bluetooth LE service described as UART or serial typically uses a different GATT-based interface.

Guide: Bluetooth Serial Adapters: Compatibility, Setup, and Testing

Reference: Bluetooth SIG: Serial Port Profile

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Security & privacySpyware

Software that covertly collects information about a person or organization without their knowledge or authorization. It may monitor activity or transmit collected data to another party. The collection behavior and permissions are the key questions when investigating it; symptoms such as a slow device can have many other causes.

Guide: Spyware: Warning Signs, Exposure, and Recovery

Reference: NIST: spyware

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Web & documentsSQL

Structured Query Language: a language for defining, querying and changing data in relational database systems. Products support different dialects; an application should pass untrusted values through parameters rather than concatenate them into SQL text.

Read the guide: SQL Explained with Queries You Can Follow

Reference: SQLite SELECT documentation

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Computers & specificationsSSD

Solid-state drive: persistent storage that uses solid-state memory, commonly flash. Capacity, interface and workload affect its usefulness; an SSD stores files while system RAM holds active working data.

Read the guide: Technology Terms That Help You Read Product Specifications

Reference: Kingston: memory and storage

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NetworksSSID

Service Set Identifier: the name used to identify a Wi-Fi network. Several access points can advertise the same SSID, and an unrelated transmitter can copy the name. Use the venue’s official connection instructions and expected security settings when choosing a network; the displayed name alone does not establish who operates it.

Guide: Airport Wi-Fi: Find the Official Network and Get Connected

Reference: Microsoft: the 802.11 service set identifier

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Historical names & systemsSSR (Elpida memory)

Super Self Refresh, an Elpida name for a memory power-saving feature in historical DDR SDRAM coverage. It describes that product feature rather than a universal capability of all memory modules.

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Science & measurementStandard deviation

A measure of how widely values vary around their mean, expressed in the same units as the observations. The usual sample calculation squares the deviations from the sample mean, sums them, divides by n − 1, then takes the square root. Population calculations use a different convention. Standard deviation describes spread; standard error describes uncertainty in an estimated statistic.

Guide: Pipetting: Improve Accuracy, Precision, and Repeatability

Reference: NIST: sample standard deviation (PDF)

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Rocks & EarthStorm surge

The rise in coastal water level caused by a storm above the predicted astronomical tide, driven mainly by winds pushing water toward the coast. Storm tide combines surge with the tide; waves add further effects. Read surge guidance separately from a hurricane's wind category and center track, using current local evacuation information for decisions.

Guide: Hurricanes: Read the Forecast and Prepare for Each Hazard

Reference: National Hurricane Center: storm surge and storm tide

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Business & organizationsSTTR

Small Business Technology Transfer, a U.S. research program involving collaboration between small businesses and research institutions. Current agency rules define participation and funding opportunities.

Related coverage: Ferrium C61 C64 alloys

Reference: SBIR and STTR programs

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Rocks & EarthSurface reflectance

An estimate of how a surface reflects incoming light within a wavelength band. Satellite surface-reflectance products correct measurements for atmospheric scattering and absorption to support comparisons of surface properties. Interpretation still depends on the product, viewing conditions and quality flags; apply its documented scaling and screen clouds and shadows before comparing numerical values.

Guide: Earth Imaging: Choose and Compare Satellite and Aerial Images

Reference: NASA LAADS DAAC: atmospherically corrected surface reflectance

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Historical names & systemsSVN (network simulation)

Software virtual network, a phrase used in Scalable Network Technologies' historical communications-simulation coverage. Here it means a modeled network environment; the model's assumptions bound what its results establish.

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Food & cookingSweating (cooking)

Gently cooking vegetables in a small amount of fat until they soften and release moisture, while keeping browning minimal. Often used for onions and other aromatics at the start of a soup or sauce. Follow the recipe's texture and color cues; sautéing typically uses a hotter pan for quicker cooking.

Guide: Sautéing: Heat, Pan Space and Three Useful Methods

Reference: Escoffier teaching text: sweating and dry-heat methods (PDF)

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NetworksSwitch fabric

The internal interconnection that carries traffic between a device's input and output interfaces. Its architecture and capacity contribute to how the device handles simultaneous traffic.

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A starting point for understanding

Each entry gives a concise meaning and, where useful, a distinction or practical example. Topic labels identify the context; the same acronym can have several meanings. Historical names remain useful when reading older coverage.

Follow the linked Yenra guides for fuller explanations and the reference links for supporting documentation. Health, technical and regulatory terms describe concepts; individual decisions depend on the applicable evidence, equipment and circumstances.

Collection updated October 13, 2026. Full glossary · AI Glossary