Glossary F - Yenra

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

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Switching service or traffic to an alternative resource when the active one fails or becomes unsuitable. A multi-WAN router can direct traffic to a backup internet connection after a health check detects trouble. Detection time, address changes and application behavior affect continuity, so verify what happens to an active call or session during a controlled test.

Guide: Wireless Bandwidth Aggregation: Bonding, Balancing and Failover

Reference: Peplink: backup links and failover behavior

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Science & measurementFAIR principles

Guidelines for making digital research resources Findable, Accessible, Interoperable and Reusable. They emphasize persistent identifiers, useful metadata, shared formats and vocabularies, provenance and clear reuse conditions, including machine-readable information. Accessible resources can require authentication and authorization: FAIR supports documented access arrangements as well as openly downloadable data.

Guide: E-Science: Build a Reproducible Research Workflow

Reference: GO FAIR Foundation: FAIR Guiding Principles

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Security & privacyFalse positive

A result that reports a target condition when that condition is absent. A spam filter marking a legitimate message as spam is a false positive. A false negative misses a condition that is present. Define the target and inspect examples of both errors when judging a filter’s usefulness.

Guide: SpamSquelcher and the Challenge of Accurate Spam Filtering · Confusion Matrix (AI Glossary)

Reference: NIST: false positive

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Historical names & systemsFAST (EMC storage)

Fully Automated Storage Tiering, EMC's name for technology that moved data between storage tiers according to policy and activity. Historical product claims should be read with the specific platform and software release.

Related coverage: EMC FAST fully automated storage tiering

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NetworksFault tolerance

The ability to continue a specified service when a component or operation fails. Its extent depends on the failure types covered and on whether redundant parts share a common vulnerability.

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Computers & specificationsFederated learning

Training a shared machine-learning model by exchanging model updates across devices or organizations while the training data remain with their holders. Additional controls are needed to address information that updates themselves may reveal.

Reference: NIST: federated learning

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Health & careFeLV

Feline leukemia virus, a retrovirus that infects cats and can affect their immune and blood-forming systems. Veterinary testing is needed to interpret an individual cat's infection status.

Reference: Cornell: feline leukemia virus

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Health & careFHIR

Fast Healthcare Interoperability Resources, HL7's framework for exchanging health information through defined resources and interfaces. An implementation must identify its FHIR version and applicable profiles to establish compatibility.

Reference: HL7 FHIR summary

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NetworksFHSS

Frequency-hopping spread spectrum: transmitting by moving among radio frequencies according to an agreed sequence. The hopping pattern and channel use belong to the particular radio system.

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Science & measurementFID (animal behavior)

Flight-initiation distance: the distance between an approaching disturbance and an animal when the animal begins to flee. The species, approach and surrounding conditions matter when comparing observations.

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Computers & specificationsFile system

The rules and structures a system uses to organize, name, store and retrieve files on a storage volume. Examples include exFAT, NTFS and APFS. Check read and write support on every intended device before choosing a format; the drive’s connector and physical storage technology describe separate compatibility requirements.

Guide: Portable Storage: SSDs, Hard Drives, Connections, and Backups

Reference: Microsoft: how file systems organize stored files

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Security & privacyFirewall

A control that permits or blocks network traffic according to rules. A firewall may run on a device or at a boundary between networks. Its coverage depends on where traffic passes and what its rules inspect; antivirus scanning and account permissions perform different jobs.

Guide: Network Antivirus Firewalls: Traffic Inspection, Coverage, and Limits

Reference: NIST: firewall

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Computers & specificationsFireWire

A name for the IEEE 1394 serial-interface family, also encountered as i.LINK on some video equipment. It has been used for digital-video transfer and external storage. Identify the equipment’s port, supported transfer mode and computer-driver requirements; matching connectors or a passive cable alone cannot supply a missing interface protocol.

Guide: DV Disk Recorders: Transfer and Check FireStore Footage

Reference: Focus Enhancements: FS-4 HD FireWire interfaces and transfer modes (PDF)

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Computers & specificationsFirmware

Software and associated data stored in a device to support its operation and hardware functions. A firmware version can affect a receiver’s features, compatibility or behavior. Record the exact device model and installed version when seeking support, and use the manufacturer’s matching update package and procedure.

Guide: GPS Chipsets and GNSS Modules: Selection and Integration

Reference: NIST: firmware

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Health & careFIV

Feline immunodeficiency virus, a virus that attacks a cat's immune system. It is distinct from feline leukemia virus; a veterinarian interprets testing and care needs for the individual animal.

Reference: Cornell: feline immunodeficiency virus

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Transport & aerospaceFlight recorder

An aircraft recording system that preserves information useful for reconstructing flight events. A flight data recorder stores selected parameters, such as altitude and airspeed; a cockpit voice recorder captures cockpit sounds and communications. These are distinct recording functions. Investigators interpret the recovered records together with other evidence when determining what happened.

Guide: Aircraft Black Boxes: What Flight Recorders Can Reveal

Reference: NTSB: cockpit voice and flight data recorders

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Computers & specificationsFlow control

A mechanism that regulates sending so a receiver or intermediate buffer can keep up. Serial connections may use hardware readiness signals, such as RTS/CTS, or software control characters, such as XON/XOFF. Both ends need compatible settings and any required wiring; successful flow control does not by itself confirm that an application processed a message.

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

Reference: Digi: serial buffering and flow control

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PhotographyFocal length

An optical property of a lens, usually stated in millimeters, that helps determine angle of view for a given sensor or film format. At the same format, longer focal lengths give a narrower view. An equivalent focal-length label compares angle of view across formats; it does not change the lens’s actual focal length.

Guide: Landscape Photography: Plan the Frame, Light, and Exposure

Reference: Nikon: focal length and angle of view

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Transport & aerospaceFOPS

Falling-object protective structure: a protective structure intended to reduce an equipment operator's exposure to falling objects. Its tested protection level and suitability belong to the exact machine and applicable standard.

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Rocks & EarthForecast cone

The area shown around the National Hurricane Center's forecast center track to represent track uncertainty. Its circles are sized from historical forecast errors, with two-thirds of those errors inside the circle at each lead time. The cyclone's wind, rain and surge hazards extend beyond its center, so read the separate hazard products alongside the cone.

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

Reference: National Hurricane Center: definition of the track forecast cone

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AccessibilityForm label

Text that identifies a form control’s purpose, such as Email address beside an input. In HTML, a label element can be associated with a control by matching its for attribute to the control’s unique id, or by containing the control. This relationship helps supply its accessible name; placeholder text is an unreliable substitute for a persistent label.

Guide: Accessibility Evaluation and Repair: From Finding to Retest

Reference: W3C: associating labels with form controls

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Web & documentsFragment (URL)

The part of a URL following #, used to identify a location or component within a resource. In a web page it commonly points to an element's ID, such as #term-url; the browser handles it separately from the HTTP request target.

Read the guide: How to Read a URL: Domains, Paths, Queries, and Fragments

Reference: WHATWG URL standard

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Audio & videoFrame rate

The number of image frames represented or displayed per second, usually written as fps. Read it alongside the scan type: interlaced field counts describe a different quantity. A label such as 30 fps may also stand for a nearby fractional rate, so inspect the exact timing before editing or converting footage.

Guide: HDV Format: Identify, Capture and Edit Older HD Video

Reference: Adobe: video timing and fields

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Historical names & systemsFrame Relay

A wide-area networking technology that carries frames over virtual circuits. Records for inherited services may describe local circuit identifiers, access rates and committed information rates.

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Transport & aerospaceFreeze-frame data (vehicle)

A stored snapshot of selected vehicle operating values associated with a detected fault, such as engine speed, load or temperature. Read it alongside the related diagnostic trouble code to understand the conditions around the event. Save available records before clearing codes, because clearing can remove this context; the captured fields and retention depend on the system.

Guide: Automotive Diagnostics: From a Reported Symptom to a Verified Repair

Reference: OBD Auto Doctor: freeze-frame data and retention

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NetworksFresnel zone

One of the ellipsoidal regions around a radio path used to assess how obstacles affect propagation. For a point-to-point wireless link, clearance of the first Fresnel zone matters as well as the direct sightline. Its size varies with wavelength and position along the path; include terrain, buildings and vegetation when evaluating the link profile.

Guide: Wireless Ethernet Bridges: Plan and Test a Building-to-Building Link

Reference: Cisco Meraki: Fresnel zones and radio path clearance

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Health & careFSGS

Focal segmental glomerulosclerosis, a pattern of scarring affecting portions of some kidney filtering units, called glomeruli. Different underlying causes can produce this pattern, so the term alone does not establish treatment or prognosis.

Reference: National Kidney Foundation: FSGS

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Computers & specificationsFull-charge capacity

The battery system’s estimate of the capacity a battery can hold when fully charged, often reported in milliwatt-hours on a laptop. Compare it with the battery’s design capacity in the same units to help assess wear. It describes estimated capacity; remaining-charge percentage and runtime under a particular workload answer different questions.

Guide: Laptop Batteries and Power Banks: Compatibility, Health, and Runtime

Reference: Microsoft: reported full-charge and design battery capacity

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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