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.
hydrocarbon consisting of two or more fused aromatic rings.
Discussion—Common examples include naphthalene, anthracene, and phenanthrene. Also known as polyaromatic hydrocarbon (PAH) or condensed ring aromatic.
Dental casting material formulated to render fine detail.
A group of organisms of the same species in a defined geographic area, such that any pair of members can interbreed.
the totality of items or units of material under consideration.
Discussion—The word "items" may be interpreted in the sense of measurements, or possible measurements, of a single characteristic, or occasionally for multiple characteristics, on all items or units of material being considered. The word "totality" may refer to items not available for inclusion in samples as well as those which are available.
totality of items under consideration.
Discussion—Note that a population may be real and finite, real and infinite, or completely hypothetical.
A group of organisms of the same species in a defined geographic area such that any pair of members can interbreed.
A group of organisms of the same species in a defined geographic area, such that any pair of members can interbreed.
Individuals grouped by shared factors such as geography, biology, culture, language, etc.
A measure (e.g., distance, probability of membership) of similarity between the individual and reference groups (see Annex A).
The study of genes and allele frequencies in populations.
The existence of subpopulations with different allele frequencies.
in facial identification, the orientation of the face with respect to the camera, consisting of pitch, roll, and yaw.
Assignment of tooth numbers based upon the location of the teeth. This is in contrast tomorphological tooth numbering, which assigns a tooth number based upon position,the shape of the tooth. For most cases, the tooth number assignment would be the same.Differences arise only in unusual cases.
A trained detection alert in the presence of the target odor/scent.
A trained detection alert in the presence of the target odor/scent.
A trained detection alert in the presence of the target odor/scent.
A trained detection alert in the presence of the target scent
A trained detection alert in the presence of the target scent
A test sample like the case sample(s) that contains the analyte(s) of interest at a known concentration
a material of established origin that is used to confirm that a procedure will produce the expected result.
An analytical control sample that is used to determine if a test performed properly; this control consists of the test reagents and a known sample that will provide an expected positive response with the test. NOTE For DNA testing, positive controls include positive amplification controls and may include extraction positive controls.
An analytical control sample that is used to determine if a test performed properly. This control consists of the test reagents and a known sample that will provide a positive response in the test.
An analytical control sample that is used to determine if a test performed properly. This control consists of the test reagents and a known sample that will provide a positive response in the test.
An integer greater or equal to 1. The value 0 is not included in this use of the term.
A type of search conducted in a specific area in which an existing human scent in the environment matches that of the scent article presented to the canine.
A type of search conducted in a specific area in which an existing human scent in the environment is associated with the scent article presented to the canine.
Within this document the positive predictive value is defined as the fraction of identifications that correspond to true known matches, TP/(TP+FP) where TP (True Positives) is the number of correctly identified Known Matches and FP (False Positives) is the number of Known Non-Matches incorrectly determined to be an Identification.
A reward given after a response or as the response occurs that increases the probability of that response recurring. For example, if a canine is rewarded for sitting by being given a treat the canine is more likely to sit again.
Checking to confirm that the natural (or usual) inputs yield the expected output.
Upon presentation of the reward article, the canine takes the article without hesitation, and maintains a firm grip.
An analytical procedure to determine the amount of amplicon obtained after DNA amplification.
After death.
A skeletal defect that occurred after a bone has lost its biomechanically fresh (visco-elastic) properties.
Examination of a decedent and associated information by a forensic pathologist or other medical personnel certified to perform such examinations; this may include autopsy, external examination, ancillary tests, evaluation of circumstances, review of medical records and other contextual information.
The time between death and discovery of the decedent or remains; also known as time since death.
The appearance of an opaque band near the root/proximal end of a hair potentially observed in anagen or catagen hairs that have been removed from a decomposing body. The possibility of other conditions causing the same or similar characteristics cannot be eliminated.
The analysis of specimens from decedents to determine the presence of drugs or other chemicals for the purpose of medico-legal death investigation.
The position in which the body is held.
The position in which the body is held.
One pound-force, 1 lbf, is defined as the weight of a one avoirdupois pound, 1 lb, mass at standard gravity.1 lbf (pound-force) 4.448 N (newtons)1 N (newton) 0.2248 lbf (pound-force)NOTE The SI unit of force is the newton, symbol N. In the U.S., it is customary to specify the trigger pull force in pound-force, symbol lbf.NOTE Pound-force lbf is sometimes referred to as pound lb where the context refers to force rather than mass.
A disparaged term for an irregular pattern that may be observed at a fire scene. This kind of pattern should not be identified as resulting from ignitable liquids on the basis of observation of the visual appearance alone.
A property of a process, such as fire, which describes the amount of energy that is emitted, transferred, or received per unit time and is measured in joules per second (J/s) or watts (W).
Pixels per inch.
Pixels per millimeter.