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.
Personal Identity Verification.
the process of combining counts from adjacent pixels in a CCD detector during readout.
A fingerprint image resulting from the touching of one or more fingers to a livescanplaten or paper fingerprint card without any rolling motion.
light in which the electric field vibrates in one direction in a single plane.
The friction ridge skin on the feet (soles and toes).
Any of a wide range of natural or synthetic organic materials of high molecular weight that can be formed by pressure, heat, extrusion, and other methods into desired shapes.
material added to plastics to impart flexibility by creating spaces between the polymer chains and lowering the inter- and intra-chain attractive forces, allowing freer movement of the chains. Discussion—Plasticizers are used in pressure sensitive backings (particularly PVC) and some adhesives to lower the glass-transition temperature and allow use at sub-ambient temperatures.
a high explosive in a pliable plastic matrix; examples include Composition C-4 (a white plastic explosive containing primarily RDX) and Semtex (a plastic explosive containing a mixture of PETN and RDX).
blades with nearly equal length and breadth and of a thickness substantially less than the width.
recorded material viewed and heard as recorded, facilitated by camcorder, cassette recorder, or other device.
in audio and video analysis, the process of determining the most suitable equipment and settings for producing the highest quality output signal.
(1) the number of single yarns twisted together to form a plied yarn, or the number of plied yarns twisted together to form cord; (2) an individual yarn in a plied yarn or cord; (3) one of a number of layers of fabric; (4) the number of layers of fabric as a shirt collar, or of cord in a tire.
crystals resembling pliers, generally X-shaped.
The column of hot gases, flames, and smoke rising above a fire; also called convection column, thermal updraft, or thermal column.
Portable Network Graphics.
The physical location within the area of origin where a heat source, a fuel, and an oxidizing agent first interact, resulting in a fire or explosion.
An open area search method in which the canine team moves in a straight line from one designated location (point) to another.
a bundle of light rays with a single propagation direction and a single perpendicular vibration direction.
a microscope equipped with two polarizing filters, one below the stage (the polarizer) and one above the stage (the analyzer).
Discussion—When the polarizer and analyzer are inserted into the light path and orientated at 90° to each other, then objects are being observed under crossed polars.
Viewing a sample on a compound microscope that has been fitted with special filters that orient the light rays, providing analytical information about the sample.
A process whereby a document is sealed between two sheets of polyester film to preserve, stabilize, and facilitate handling.
An enzyme that catalyzes the synthesis of nucleic acids on preexisting nucleic acid templates.
An enzymatic process by which a specific region of DNA is replicated during repetitive cycles that consist of the following: denaturation of the template; annealing of primers to complementary sequences at an empirically determined temperature; and extension of the bound primers by a DNA polymerase. The goal of the PCR process is to generate many copies (termed products or amplicons) of a specific region of DNA for further analysis.
An enzymatic process by which a specific region of DNA is replicated during repetitive cycles that consist of the following: denaturation of the template; annealing of primers to complementary sequences at an empirically determined temperature; and extension of the bound primers by a DNA polymerase. The goal of the PCR process is to generate many copies (termed products or amplicons) of a specific region of DNA for further analysis.
An enzymatic process by which a specific region of DNA is replicated during repetitive cycles that consist of the following: denaturation of the template; annealing of primers to complementary sequences at an empirically determined temperature; and extension of the bound primers by a DNA polymerase. The goal of the PCR process is to generate many copies (termed products or amplicons) of a specific region of DNA for further analysis.
An enzymatic process by which a specific region of DNA is replicated during repetitive cycles that consist of the following: denaturation of the template; annealing of primers to complementary sequences at an empirically determined temperature; and extension of the bound primers by a DNA polymerase. The goal of the PCR process is to generate many copies (termed products or amplicons) of a specific region of DNA for further analysis.
The occurrence in a population of two or more alleles or physical traits at a genetic locus. This variation within a population permits the differentiation of individuals via DNA testing or physical traits.
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.
totality of items under consideration.
Discussion—Note that a population may be real and finite, real and infinite, or completely hypothetical.
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.
in facial identification, the orientation of the face with respect to the camera, consisting of pitch, roll, and yaw.
A trained detection alert in the presence of the target scent
A trained detection alert in the presence of the target 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 odor/scent.
A test sample like the case sample(s) that contains the analyte(s) of interest at a known concentration
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.
a material of established origin that is used to confirm that a procedure will produce the expected result.
An integer greater or equal to 1. The value 0 is not included in this use of the term.