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.
The measurement of light values of objects in an image.
The measurement of light values of objects in an image
Photosensitive vacuum tube device that quantitatively converts photons of light into electrical energy.
Photosensitive vacuum tube device that quantitatively converts photons of light into electrical energy
A criterion used to guide the selection of species for comparative analysis and species determination; the selection of species is based on genetic relatedness.
In computer forensics, an accurate repro- duction of information contained on a physical digital data storage device.
In computer forensics, an accurate reproduction of information contained on a physical digital data storage device
an association based upon the realignment of two or more items that demonstrate they were once joined together to form a single object.
Discussion—The term match (for example, physical match, fracture match) is not recommended to be used as it can be misleading to the layperson.
In computer forensics,a bit stream duplicate of data contained on a physical digital data storage device.
In computer forensics, a bit stream duplicate of data contained on a physical digital data storage device
Any external storage material of the voice signal and content information in eitheranalog or digital form. Examples include reel-to-reel recording tape, cassette tape,Compact Disc, and phonograph record.
The dimensions, shapes, spacing and relative positions of the footwear outsole design components and tire tread blocks (not the same as the manufacturer's footwear or tire size). Physical size is a class characteristic.
a finely-divided insoluble material used to deluster or color fibers (for example, titanium dioxide and iron oxide).
A finely ground, inorganic or organic, insoluble, and dispersed particle; besides color, pigments provide many of the essential properties of paint such as opacity, hardness, durability, and corrosion resistance; the term pigment includes extenders.
A finely ground, organic or inorganic, insoluble, and dispersed particle. Besides color, a pigment can provide many of the essential properties of paint, such as opacity, hardness, durability, and corrosion resistance (see also effect pigment).
A finely ground, inorganic or organic, insoluble, and dispersed particle; besides color, pigments provide many of the essential properties of paint such as opacity, hardness, durability, and corrosion resistance; the term pigment includes extenders
A finely ground, inorganic or organic, insoluble, dispersed particle. Besides color, a pigment can provide many of the essential properties of paint, such as opacity, hardness, durability, and corrosion resistance. The term pigment includes extenders.
Clusters of pigment granules.
clusters of pigment granules.
The relative abundance of pigment granules in the hair cortex as described along a continuum (for example, sparse, medium, heavy).
the relative abundance of pigment granules in the hair cortex as described along a continuum (for example, sparse, medium, heavy).
The pattern or arrangement of the pigment granules in the hair shaft, such as uniform, peripheral, one-sided, variable, or central.
the pattern or arrangement of the pigment granules in the hair shaft, such as uniform, peripheral, one-sided, variable, or central.
Small particles in hair composed of melanin that impart color. DiscussionMelanin is a natural pigment of which two forms, eumelanin (brown to black) and phaeomelanin (reddish brown to yellow), determine the color of human and animal hair.
small particles in hair com- posed of melanin that impart color.
Discussion—Melanin is a natural pigment of which two forms, eumelanin (brown to black) and phaeomelanin (reddish brown to yellow), determine the color of human and animal hair.
A hair disorder causing hairs to appear ringed or banded due to the alternating light and dark bands in the hair shaft; the dark bands are a manifestation of abnormal air spaces in the cortex.
a hair disorder causing hairs to appear ringed or banded due to the alternating light and dark bands in the hair shaft. The dark bands are a manifestation of abnormal air spaces in the cortex.
A hair disorder characterized by the hair shaft being flattened and twisted 180 degrees numerous times along its axis; it is usually found at irregular intervals along the shaft.
a hair disorder characterized by the hair shaft being flattened and twisted 180 degrees numerous times along its axis. It is usually found at irregular intervals along the shaft.
See ignition temperature.
a microscope equipped with two polarizing filters, one below the stage (the polarizer) and one above the stage (the analyzer).
In facial identification, an intrinsic rotation of the head about a horizontal left-to-right (lateral) axis measured in degrees. DISCUSSIONFrontal poses have a pitch angle of 0. Positive angles represent faces looking down (a counter-clockwise rotation around the axis). The pitch axis is typically defined as the X-axis (positive to the right).
In facial identification, an intrinsic rotation of the head about a horizontal left-to-right (lateral) axis measured in degrees
The circumferential length allotted for a single tire tread element, as designated on the blue print drawing for each tire design and size.
The full arrangement of pitch lengths around the full circumference of a tire, specific to a certain design and size.
Personal Identity Verification.
The process of combining counts from adjacent pixels in a CCD detector during readout.
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.
Illumination consisting of light rays with a single vibration direction.
Emitted or observed 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.
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).
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. DiscussionPlasticizers are used in pressure sen- sitive backings (particularly PVC) and some adhesives to lower the glass-transition temperature and allow use at sub-ambient temperatures.
Blades with nearly equal length and breadth and of a thickness substantially less than the width.
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.
Recorded material viewed and heard as recorded, facilitated by camcorder, cassette recorder, or other device