ExpertGlossary terms starting with F

2,087 terms

Freedom of Information Act (FOIA) A Federal law that mandates that all the records created and kept by Federal agencies in the executive branch of government must be open for public…
Freedom of Information Act (FOIA) Request A request, made based on the provisions of the Freedom of Information Act, for access to restricted information in Federal records held by NARA, including…
freely available Means you don't have to pay money to get it, but the copyright on it may still belong to someone else (like Larry).
freely redistributable Means you're not in legal trouble if you give a bootleg copy of it to your friends and we find out about it.
freenet A system of computer networks (usually funded by individuals or organizations) consisting of community-based bulletin board systems with, e.g.
freeware Historically, any software that you give away, particularly if you make the source code available as well. Now often called open source software.
Freeze A freeze is when the surface air temperature is expected to be 32°F or below over a widespread area for a climatologically significant period of time.
freeze drying process of stabilizing water-soaked documents by freezing them to prevent further damage from water in its liquid state See also vacuum drying, vacuum…
freeze frame A frame of visual information that is selected from a set of motion video frames, and is held in a buffer.
freeze frame television Television in which fixed ("still") images are transmitted sequentially at a rate far too slow to be perceived as continuous motion by human vision.
freeze notice See legal hold.
freeze preservation See: cryobiological preservation.
Freeze Warning Issued during the growing season when surface temperatures are expected to drop below freezing over a large area for an extended period of time…
freeze-dried A method used to dry substances, such as food, to make them last longer. The substance is frozen and then dried in a vacuum.
freeze-dry The removal of water as vapour from frozen material under vacuum. Used to measure water content and to preserve samples, particularly spores.
freeze-out The condition that occurs when an earlier nonactive speaker on an input transmission trunk channel becomes active and cannot immediately be assigned to a…
freeze-out fraction The ratio of the total time that the individual channels experience the freeze-out condition to the total time of the active intervals, and their…
Freeze-thaw damage Damage to concrete caused by extreme temperature variations as noted by random pattern cracking.
Freezeout Deeply frozen over for long periods of time.
Freezeup date Date on which the water body was first observed to be completely frozen over.
Freezing Drizzle A drizzle that falls as a liquid but freezes into glaze or rime upon contact with the cold ground or surface structures.
Freezing Drizzle Advisory Issued when freezing rain or freezing drizzle is forecast but a significant accumulation is not expected.
Freezing Fog A suspension of numerous minute ice crystals in the air, or water droplets at temperatures below 0Âº Celsius, based at the Earth's surface, which…
Freezing Level The altitude at which the air temperature first drops below freezing.
Freezing Rain Rain that falls as a liquid but freezes into glaze upon contact with the ground.
Freezing Rain Advisory Issued when freezing rain or freezing drizzle is forecast but a significant accumulation is not expected.
Freezing Spray An accumulation of freezing water droplets on a vessel caused by some appropriate combination of cold water, wind, cold air temperature, and vessel…
Freezing Spray Advisory An advisory that may be issued within the Offshore Waters Forecast, the Coastal Waters Forecast, the Nearshore Marine Forecast, and the Open Lake Forecast…
Freezup jam Ice jam formed as frazil ice accumulates and thickens.
Freight Forwarder A person whose business is to act as an agent on behalf of the shipper to arrange transportation services.
French door or French window A tall casement window that reaches to the floor, usually arranged in two leaves as a double door.
French Drain A covered ditch containing a layer of fitted or loose stone or other pervious material.
French Wheel Same as European Wheel.
Freon A registered trademark for a cholorfluorocarbon (CFC) gas that is highly stable and that has been historically used as a refrigerant.
Frequency The number of cycles through which an alternating current passes per second; in the U.S.
frequency accuracy The degree of conformity to a specified value of a frequency.
frequency aging Of an oscillator, the change in frequency, over time, caused by internal changes in oscillator parameters even when external factors, such as environment…
frequency allocation See allocation (of a frequency band).
frequency allotment See allotment (of a radio frequency or radio frequency channel).
frequency assignment Authorization, given by an Administration, for a radio station to use a radio frequency or radio frequency channel under specified conditions 2.
frequency assignment authority The power granted an Administration, or its designated or delegated leader or agency via treaty or law, to specify frequencies, or frequency bands, in the…
frequency averaging The process by which the relative phases of precision clocks are compared for the purpose of defining a single time standard. 2.
frequency band See electromagnetic spectrum.
frequency band allocation See allocation (of a frequency band).
frequency coherence See phase coherence.
frequency compatibility 1. Of an electronic device, the extent to which it will operate at its designed performance level in its intended operational environment (including the…
Frequency Curve A curve that expresses the relation between the frequency distribution plot, with the magnitude of the variables as abscissas and the number of…
Frequency demand scheduling Method of irrigation scheduling similar to demand scheduling, but typically involves a fixed duration of the delivery, such as 24 hours.
frequency departure The difference between the instantaneous frequency of a digital signal and the long-term average frequency of that signal. [T1.Rpt17-1993] 2.
frequency deviation The amount by which a frequency differs from a prescribed value, such as the amount an oscillator frequency drifts from its nominal frequency. 2.
frequency dispersal An electronic counter-countermeasure (ECCM) in which communications nets' operating frequencies are widely separated from each other, causing a…
frequency displacement The end-to-end shift in frequency that may result from independent frequency translation errors in a circuit.
frequency distortion Synonym amplitude-vs.-frequency distortion.
frequency diversity Transmission and reception in which the same information signal is transmitted and received simultaneously on two or more independently fading carrier…
frequency drift An undesired progressive change in frequency with time. Note 1: Causes of frequency drift include component aging and environmental changes.
frequency fluctuation A short-term variation, with respect to time, of the frequency of an oscillator.
frequency flutter A deviation of frequency that generally results from irregular motion of the recording medium during the recording, duplication, or reproduction. [T1.
frequency frogging The interchanging of the frequencies of carrier channels to accomplish specific purposes, such as to prevent feedback and oscillation, to reduce…
frequency guard band A frequency band deliberately left vacant between two channels to provide a margin of safety against mutual interference.
frequency hopping [The] repeated switching of frequencies during radio transmission according to a specified algorithm, to minimize unauthorized interception or jamming of…
frequency hour One frequency used for one hour regardless of the number of transmitters over which it is simultaneously broadcast by a station during that hour. [47CFR]
frequency instability See frequency stability.
frequency lock The condition in which a frequency-correcting feedback loop maintains control of an oscillator within the limits of one cycle.
Frequency Management The act of allocating frequencies, or bandwidths to a telecommunications system, necessary to minimize the potential interference between…
Frequency Modulation (FM) Modulation in which the instantaneous frequency of a sine wave carrier is caused to depart from the center frequency by an amount proportional to the…
frequency of optimum traffic (FOT) Synonym FOT.
frequency of optimum transmission (FOT) See FOT.
frequency offset The difference between the frequency of a source and a reference frequency.
frequency prediction A prediction of the maximum usable frequency (MUF), the optimum traffic frequency, and the lowest usable frequency (LUF) for transmission between two…
frequency range A continuous range or spectrum of frequencies that extends from one limiting frequency to another.
frequency response See insertion-loss-vs.-frequency characteristic.
frequency response curve A plot of the gain or attenuation of a device, such as an amplifier or a filter, as a function of frequency.
frequency scanning Conducting a search for signals over a band or range of frequencies by means of a manually or automatically tuned receiver. Note: The tuning rate, i.e.
frequency sharing The assignment to or use of the same radio frequency by two or more stations that are separated geographically or that use the frequency at different…
frequency shift Any change in frequency. 2. Any change in the frequency of a radio transmitter or oscillator.
frequency source See frequency standard.
frequency spectrum See electromagnetic spectrum.
frequency spectrum congestion The situation that occurs when many stations transmit simultaneously using frequencies that are close together, i.e.
frequency stability The degree to which variations of the frequency of an oscillator deviate from the mean frequency over a specified period of time.
frequency standard A stable oscillator used for frequency calibration or reference. Note 1: A frequency standard generates a fundamental frequency with a high degree of…
frequency synthesizer A device that produces frequencies that are phase coherent with a reference frequency.
frequency tolerance The maximum permissible departure by the center frequency of the frequency band occupied by an emission from the assigned frequency, or by the…
frequency translation The transfer of signals occupying a specified frequency band, such as a channel or group of channels, from one portion of the frequency spectrum to…
frequency-analysis compaction Data compaction accomplished by using an expression composed of a number of different frequencies of different magnitudes to represent a particular curve.
frequency-change signaling A signaling method in which one or more discrete frequencies correspond to each desired significant condition of a code.
frequency-derived channel A channel derived by dividing an allocated or available bandwidth over a medium into two or more portions, each usable separately.
frequency-division multiple access (FDMA) The use of frequency division to provide multiple and simultaneous transmissions to a single transponder.
frequency-division multiplexing (FDM) The deriving of two or more simultaneous, continuous channels from a transmission medium by assigning a separate portion of the available frequency…
frequency-exchange signaling Frequency-change signaling in which the change from one significant condition to another is accompanied by decay in amplitude of one or more frequencies…
frequency-hopping spread spectrum A signal structuring technique employing automatic switching of the transmitted frequency.
frequency-shift keying (FSK) Frequency modulation in which the modulating signal shifts the output frequency between predetermined values.
frequency-shift modulation Synonym frequency-shift keying.
frequency-shift signaling Synonym frequency-shift keying.
frequency-shift telegraphy Telegraphy by frequency modulation in which the telegraph signal shifts the frequency of the carrier between predetermined values. [NTIA] [RR]
Frequent Independent Travel (F.I.T.) A custom-designed, prepaid travel package with many individualized arrangements. F.I.T. are unescorted and usually have no formal itinerary.
frequently asked questions See FAQ file.
Frequently Asked Questions (FAQ) On the Superfund Web site, you may search for frequently asked questions by topic or by typing in a keyword or phrase.
Frequently Asked Questions About Contaminants Found at Hazardous Waste Sites (ToxFAQs) ATSDR ToxFAQs is a series of summaries about hazardous substances being developed by the ATSDR Division of Toxicology.
Fresh The term that Google uses to refer to frequently changing home pages. When Googlebot ascertains that a given home page is changing frequently, Googlebot…
Fresh Content Content which is dynamic in nature and gives people a reason to keep paying attention to your website.