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 term used to describe a specific pattern or arrangement of design elements on a tire treadtypically associated with a manufacturer and having a name and/or style number (also used todescribe footwear outsoles).
Bands of raised rubber, sometimes called wear bars, that are 2/32 of an inch above the bottom of the main grooves of a tire.
sensor in a flatbed scanner, or digital scanning back, which is made up of three rows of pixels with a red filter covering one row, a green filter covering the second row and a blue filter covering the third row.
a condition characterized by apparent or actual knotting of the hair.
a condition characterized by longitudinal splitting or fraying of the hair shaft.
a genetic disease characterized by a segment of bulbous, dilated hair enfolded into a concave hair terminal, recalling the appearance of a bamboo node; if the hair breaks at the bulbous end, the hair has a "golf-tee" shaped end.
a condition characterized by the formation of nodes; the hair is weaker at the node and subject to breakage.
condition in which the hair readily breaks or splits along transverse cracks.
The amount of force which must be applied to the trigger of a firearm to cause sear release. The direction of the applied force is approximately parallel to the bore axis.b
The amount of force which must be applied to the trigger of a firearm to cause sear release.
an ester of three fatty acids and glycerol.
Discussion—Triglycerides are the chief constituent of animal fats and vegetable oils; some triglycerides are susceptible to spontaneous heating when exposed to air.
smokeless powder that contains nitrocellulose, nitroglycerin, and nitroguanidine.
propellant containing nitrocellulose, nitroglycerin, and nitroguanidine.
A conversation is a sequence of conversational turns. A turn is when an individualspeaks for a continuous period of time. Individual turns from different people mayoverlap when they speak simultaneously. However, typically a turn is referred to in aquestion / response environment.
the number of turns about the axis applied to a fiber, yarn, strand, or rope over a given length to combine the individual elements into a larger and stronger structure.
Discussion—The direction of twist in yarns is indicated by the capital letters S and Z. A yarn has an S-twist if, when it is held vertically, the spirals around its central axis slope in the same direction as the middle portion of the letter S, and Z-twist if they slope in the same direction as the middle portion of the letter Z.
Method of evaluation of uncertainty by the statistical analysis of series of observations (e.g., relative standard deviation of a historical data set of control results)
Method of evaluation of uncertainty by means other than the statistical analysis of series of observations (e.g., obtaining the uncertainty associated with a CRM from its certificate of analysis)
This is the mistake when one rejects the null hypothesis (one states that there is an effect) and it is true (there is really NO effect). This is also called a false positivedetecting an effect where none exist. (see false positive.)
This is the mistake when one accepts the null hypothesis (there is no effect) when it is false (there really IS an effect). This is also called a false negativefailure to detect a real effect. (see 3.162 false negative.)
individual fibers from a technical fiber (see technical fiber).
Electromagnetic radiation with a wavelength from 100 nm (30 PHz) to 380 nm (750 THz), which, when used as a light source, can fluoresce dental materials for better visualization and location.
Referring to radiant flux having wavelengths shorter than the wavelengths of light, usually wavelengths from about 10 nm to 380 nm.
(1) areas on storage media which a file system has marked as available for use for data storage, (2) the portions of storage media that are unassigned external to a file system.
Discussion—The area may already contain previously stored information. Also referred to as free space.
See classical conditioning.
An alert for which the presence of a trained odor/scent cannot be confirmed. This may be the result of residual or lingering odor/scent that the canine can detect but which has not been confirmed by technology or direct observation. (See non-productive response.)
Lack of verification of search results following a deployment of a canine team(s).
Lack of verification of search results following a deployment of a canine team(s).
Lack of verification of search results following a deployment of a canine team(s).
Lack of verification of search results following a deployment of a canine team(s)
Lack of verification of search results following a deployment of a canine team(s)
Lack of verification of search results following a deployment of a canine team(s)
in facial identification, an image not captured in accordance with facial identification/facial recognition (FI/FR) standards or guidelines (for example, a surveillance image).
A written or oral consensus between the interested parties concerning the management of the investigations.
Manner of death used when the information pointing to one manner of death is no more compelling than another after thorough consideration of all available information.
A computing industry standard for the representation of most of the world's scripts (suchas Latin letters, Cyrillic letters, Chinese characters, special symbols and others). See A.
A scenario where the laboratory has concluded that the data do not support or refute a proposition as defined by the laboratory and based on validation studies.
The inability to use results for comparisons due to poor or limited data quality.
the smallest group of atoms of a crystal lattice that has the overall symmetry of a crystal of that substance and from which the entire lattice can be built up by repetition in three dimensions.
Measures taken to ensure safety under the assumption that any unknown materials or situations present the most dangerous scenario possible.
Data that cannot be used for comparisons for reasons including, but not limited to, poor or limited data quality, mixture complexity, or a failure to meet quality assurance requirements.
Data that cannot be used for comparisons for reasons including, but not limited to, poor or limited data quality, mixture complexity, or a failure to meet quality assurance requirements.