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.
Imaging technique with light transmitted through an excised specimen.
A mutation that results in a change from one purine to the other purine (e.g., A-to-G) or one pyrimidine to the other pyrimidine (e.g., C-to-T).
Illumination that passes through a document.
A container used to appropriately move training aids in compliance with storage and handling guidelines of the Federal, state, and/or local agencies' policy.
A mutation that results in a change from a purine to pyrimidine or vice versa (e.g., A-to-T).
Reporting of the location, dimension(s), and other observed characteristics of the skeletal defect(s).
Explanation regarding the mechanism, timing, direction of impact(s), and/or minimum number of impacts associated with skeletal defect(s) using quantitative and/or qualitative evidence.
The external factors that produce a skeletal defect.
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).
Referring to radiant flux having wavelengths shorter than the wavelengths of light, usually wavelengths from about 10 nm to 380 nm.
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.
(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)