OSAC Lexicon
The OSAC Lexicon is a compendium of forensic science terms and definitions. This terminology tool was created to help bring consistency and understanding to the way terms are used by the various forensic science. Use of the OSAC Lexicon does not replace the need to reference the original published source.
The terms and definitions in the OSAC Lexicon come from the published literature, including documentary standards and technical reports. It is continually updated with the latest work from OSAC units, as well as terms from newly published documentary standards and standards elevated to the OSAC Registry.
Gradually terms are evaluated and harmonized by the OSAC to a single term. This process results in an OSAC Preferred Term. An OSAC Preferred Term is a term, along with its definition, that has undergone review and evaluation by the FSSB Terminology Task Group and has been approved by the FSSB. The FSSB recommends that subcommittees use OSAC Preferred Terms when drafting standards.
The OSAC Lexicon should be the primary resource for terminology and used when drafting and editing forensic science standards and other OSAC work products.
A structured approach to predicting one or more effects of a fire.
The physical changes, or identifiable shapes, formed by a fire effect or group of fire effects.
See fire spread.
Systems, devices, and equipment used to detect a fire and its by-products, actuate an alarm, or suppress or control a fire and its by-products, or any combination thereof.
The process of recreating the physical scene during fire scene analysis investigation or through the removal of debris and the placement of contents or structural elements in their pre-fire positions.
The body of knowledge concerning the study of fire and related subjects (such as combustion, flame, products of combustion, heat release, heat transfer, fire and explosion chemistry, fire and explosion dynamics, thermodynamics, kinetics, fluid mechanics, fire safety) and their interaction with people, structures, and the environment.
The body of knowledge concerning the study of fire and related subjects (such as combustion, flame, products of combustion, heat release, heat transfer, fire and explosion chemistry, fire and explosion dynamics, thermodynamics, kinetics, fluid mechanics, fire safety) and their interaction with people, structures, and the environment.
The movement of fire from one place to another.
see «suppression»
see suppression.
See suppression.
A symbol used to describe the necessary requirements for fire to occur: fuel, heat, oxidizer, and an uninhibited chemical chain reaction.
a symbol to describe the necessary requirements for fire to occur: fuel, heat, oxidizer, and an uninhibited chemical reaction.
a symbol to describe the necessary requirements for fire to occur: fuel, heat, oxidizer, and an uninhibited chemical reaction.
A symbol used to describe the necessary requirements for fire to occur in which the three sides represent fuel, oxidizer, and a source of ignition. The connection of the sides to form a triangle symbolizes the chain of reaction.
The first fuel ignited is that which first sustains combustion beyond the ignition source.
Any individual responding to a crime scene, including but not limited to: law enforcement, investigative, medical, fire/paramedic, and laboratory personnel
The portion of an oral dose metabolized in the intestine, gut wall, or liver before reaching the systemic circulation.
a type of distortion, where central objects of the image erroneously appear closer than those at the edge typically resulting in what appear to be unusually large noses in the image.
Clear plastic sheet with a pressure sensitive adhesive layer.
a lens with a focal length that is not adjustable.
A schedule of reinforcement in which rewards for a correct response occur after a fixed period of time.
A schedule of reinforcement in which the subject is rewarded after a set number of unrewarded correct responses.
A process or reagent that helps secure the blood to the substrate or secures the substrate itself (e.g.,snow, sand, etc.) so that it is not destroyed or degraded during chemical enhancement.
A hot, usually luminous zone of gas that is undergoing combustion.
A body or stream of gaseous material involved in the combustion process and emitting radiant energy at specific wavelength bands determined by the combustion chemistry of the fuel. In most cases, some portion of the emitted radiant energy is visible to the human eye.
The flaming leading edge of a propagating combustion reaction zone.
The condition where unburned fuel (pyrolysate) from the originating fire has accumulated in the upper layer to a sufficient concentration (i.e., at or above the lower flammable limit) that it ignites and burns. This can occur without ignition of, or prior to the ignition of, other fuels separate from the origin.
Capable of burning with a flame.
capable of burning with a flame.
The upper or lower concentration limit at a specified temperature and pressure of a flammable gas or a vapor of an ignitible liquid and air, expressed as a percentage of fuel by volume that can be ignited.
A liquid that has a closed-cup flash point that is below 37.8C (100F) and a maximum vapor pressure of 2068 mm Hg (40 psia) at 37.8C (100F). (See also 3.3.34, Combustible Liquid.)
See ignitable liquid.
The range of concentrations between the lower and upper flammable limits.
A fire that spreads by means of a flame front rapidly through a diffuse fuel, such as dust, gas, or the vapors of an ignitible liquid, without the production of damaging pressure.
the lowest temperature corrected to a pressure of 101.3 kPa (760 mm Hg) at which application of an ignition source causes the vapors of a specimen of the sample to ignite under specified conditions of the test.
Discussion—There are several methods for determining the flash point. The preferred method used by authorities in delineating between flammable and combustible liquids is a closed-cup flash point test.
The lowest temperature of a liquid, as determined by specific laboratory tests, at which the liquid gives off vapors at a sufficient rate to support a momentary flame across its surface.
A mixture of strong inorganic oxidizer; such as perchlorate or chlorate salts; and finely divided metal fuel; such as aluminum or magnesium powders; also known as photoflash powder.
Discussion—Sulfur powder; often used as a fuel/tinder; and carbonaceous filler materials can also be present in flash powder.
A transition phase in the development of a compartment fire in which surfaces exposed to thermal radiation reach ignition temperature more or less simultaneously and, given sufficient availability of oxygen, fire spreads rapidly throughout the space, resulting in full room involvement or total involvement of the compartment or enclosed space.
A fingerprint image resulting from the touching of a single finger to a livescan platen orpaper fingerprint card without any rolling motion. Also known as a single-finger plainimpression.
smooth paper backing masking tape (saturated paper tape).
A process by which radiant flux of certain wavelengths is absorbed and reradiated nonthermally at other, usually longer, wavelengths.
the emission of light by a fiber that has absorbed light or other electromagnetic radiation of shorter wavelength (higher energy).
a microscope equipped with a high energy light source (usually a xenon or mercury vapor lamp) and a set of excitation and barrier filters along with a dichromatic mirror, used to induce and observe fluorescence in fibers and other particles or materials.
the distance from the optical center of a lens to its point of focus at the sensor or image plane when focused at infinity.
Surface topography measurement method whereby the sharpness of the surface image (or anotherproperty of the reflected light at optimum focus) in an optical microscope is used to determine thesurface height at each position along the surface.
tissue from a hair follicle that is still attached to the root end of a hair which has been forcibly removed.