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.
An abnormal connection of low resistance between normal circuit conductors where the resistance is normally much greater; this is an overcurrent situation but it is not an overload.
Multiple copies of an identical (or similar) DNA sequence arranged in direct succession where the repeat sequence unit is 2 base pairs (bp) to 6 bp in length; because STRs generally occur in the DNA outside of the constraints (i.e., selective pressure) of genes, the number of repeat units can vary between individuals;2 variations in STRs may be used for distinguishing individuals, and in biological relationship and ancestry testing
Indicates a recommendation or that which is advised but not required.
Used to indicate that a provision is not mandatory, but recommended as good practice.
Used to indicate that a provision is not mandatory, but recommended as good practice.
a variation of the hair form along the shaft, resulting in an irregular and often asymmetrical change of cross-sectional shape.
a variation of the hair form along the shaft, resulting in an irregular and often asymmetrical change of cross-sectional shape.
added materials (usually metal) which are placed in or around an explosive to intentionally produce additional property damage and injuries.
Discussion—(1) It should be noted that the term 'shrapnel' is also sometimes colloquially used to denote any pieces from a device that are fragmented by an explosion. (2) Shrapnel can also be included in some military ordnance.
Illumination from a light source at a low angle of incidence, or even parallel, to the surface of the item. Syn. oblique lighting, grazing illumination, raking lighting.
Illumination from a light source that is at a low angle of incidence, or even parallel, to the surface of the item. Syn., oblique lighting.
a property of fibers referring to the elongation of a fiber in relation to refractive indices.
Discussion—If the fiber is elongated in the direction of the higher refractive index, it is said to have a positive sign of elongation; if the fiber is elongated in the direction of the lower refractive index, it is negative.
to overwrite all available storage areas with a unique sector character sequence.
An observation that two impressions share a general likeness when comparing an individual feature or detail. Not to be confused with “agreement.”
The acquisition of images of a single biometric modality from a subject at the same time.Sequential capture over a time scale ( < 1 second) that prevents confounding of bodyparts ( e.g., substituting left iris for right iris) can also be considered simultaneous capturein this context.
DNA sequence variations that occur when a single nucleotide (A, T, C, or G) in the genome sequence is altered; these variations may be used for distinguishing individuals, and in biological relationship and ancestry testing.
Refers to a training exercise in which two subjects walk a straight line and then split into two different directions. When the canine is presented with a scent article from one of the subjects, the canine commences to trail and match the correct person to the scent article. Despite the contamination of scent from the other person on the trail the canine is still able to discriminate between scents and identify the correct subject.
smokeless powder which contains nitrocellulose but does not contain nitroglycerine or nitroguanidine.
propellant containing nitrocellulose as the major energetic material.
An evaluation of the canine team's ability to complete an exercise where the evaluator knows the outcome and the canine team does not.
An evaluation of the canine team's ability to complete an exercise where the evaluator knows the outcome and the hander does not.
An evaluation of the canine team's ability to complete an exercise where the evaluator knows the outcome and the handler does not.
A dog trained in only one discipline.
An evaluation of the canine team's ability to complete an exercise where the evaluator knows the outcome and the canine team does not.
An evaluation of the canine team's ability to complete an exercise where the evaluator knows the outcome and the canine team does not.
An evaluation of the canine team's ability to complete an exercise where the evaluator knows the outcome and the canine team does not.
name for the most commonly used primer.
Discussion—It is composed primarily of lead styphnate, barium nitrate, and antimony sulfide.
A regularly irregular heart rhythm associated with changes in breathing, normal finding in the canine.
A regularly irregular heart rhythm associated with changes in breathing, normal finding in the canine.
The general physical location of the incident, including the scene and the surrounding area deemed significant to the process of the investigation and support areas.
Osseous, cartilaginous, and/or dental tissues.
a crystal in which all of the spaces in the crystal lattice are not occupied.
Osseous, cartilaginous, and dental tissues.
A defect to osseous, dental, and/or cartilaginous tissue as a result of external forces.
Osseous, cartilaginous, and/or dental tissues.
Osseous, cartilaginous, and/or dental tissues.
A representation of a friction skin image in which all pixels are white except for a 1-pixel-wide thinned black skeleton following the midpoint of each ridge. Also known as aridge tracing.
a magnetic card reader, specifically when used for an illegal purpose.
using a skimmer to acquire PII in an unauthorized manner.
A technique involving the superimposition of a facial photograph or video of a known individual with an unidentified skull.
The accidental discharge of a firearm upon closing of the action.
Slap fingerprints (slaps) are taken by simultaneously pressing the fingers of one hand(i.e., without the thumb) onto a scanner or fingerprint card. Slaps are also known as fourfinger simultaneous plain impressions (although if the person has more than four fingerson a hand, all of the fingers may be included in the slap image).