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 study of the science, methodology, and practice of temperature measurement.
A synthetic material that softens or melts at high temperatures
Plastic materials that soften and melt under exposure to heat and can reach a flowable state.
a synthetic material that softens or melts at high temperatures.
Plastic materials that are hardened into a permanent shape in the manufacturing process and are not commonly subject to softening when heated; typically form char in a fire.
Distance from one surface of a tape, backing, or adhesive to the other, usually expressed in the United States as thousandths of an inch, or the industrial vernacular as 'mils' which represents thousandths of an inch (that is, 1 mil = 0.001 in.).
the optical path through a fiber used for the calculation of birefringence.
The optical path through a fiber used for the calculation of birefringence
For the purpose of this guide, a sample that is 2 m or thicker
For the purpose of this guide, a sample with a thickness of less than 2 m
The series of spots visible on the adsorbent layer after development
A separation technique in which the flow of solvent causes the components of a mixture to migrate differentially from a narrow initial zone over a planar, thinly-applied porous adsorptive medium
In facial identification, images used in facial recognition (FR) or facial identification (FI) that were not captured by the agency performing the comparison (for example, family snapshots of a missing person)
In facial identification, images used in facial recognition (FR) or facial identification (FI) that were not captured by the agency performing the comparison (for example, family snapshots of a missing person).
A slender strong strand or cord made by plying or twisting yarns, typically used for stitching
a slender strong strand or cord made by plying or twisting yarns, typically used for stitching.
An impression made on surfaces such as soil, sand, snow or mud with dimensions of length, width, and depth.
A value, based on a background sample study, below which the number of pGSR particles identified cannot be distinguished from background levels and thus cannot be reliably interpreted as associated with the discharge of a firearm or contact with a source of pGSR.
DetectionThe minimum and maximum concentration of a chemical vapor that can be detected by a canine or an instrument. BehavioralThe level of stimulation above or below which learning and/or performance is impaired.
Small digital storage device that uses flash memory and a universal serial bus (USB) connection to interface with a computer
In video analysis, a feature of digital video recorders (DVRs) that allows the equipment to adhere to data retention policies that may be mandated in certain parts of the world which results in video data becoming inaccessible after a certain date
In video analysis, a feature of digital video recorders (DVRs) that allows the equipment to adhere to data retention policies that may be mandated in certain parts of the world which results in video data becoming inacces- sible after a certain date.
Graphic representation of the events in a fire incident displayed in chronological order.
A electronic device used to correct timing inconsistencies, stabilize, and synchronize video signals for optimum quality
A electronic device used to correct timing inconsistencies, stabilize, and synchronize video signals for optimum quality.
Process by which images are recorded at less than the standard rate of frames per second (National Television System Committee (NTSC) 29.97; Phase Alternating Line (PAL) 25.00) thus extending the period of time that can be covered by the storage medium
Process by which images are recorded at less than the standard rate of frames per second (National Television System Committee (NTSC) 29.97; Phase Alternating Line (PAL) 25.00) thus extending the period of time that can be covered by the storage medium.
Process of relating images, audio, or other data to one another in a chronologically ordered succession
Process of relating images, audio, or other data to one another in a chronologi- cally ordered succession.
In computer forensics, a point in time with respect to system time used by a file system to annotate creation, access or modification of file system objects
In computer forensics, a point in time with respect to system time used by a file system to annotate creation, access or modification of file system objects.
the most distal end of a hair shaft.
the most distal end of a hair shaft.
Any solid biological specimen that is generally weighed for analysis (e.g., brain, liver, muscle, hair, bone, meconium).
Organization responsible for recovering tissues from tissue donors.
See vaccine titer.
See vaccine titer.
The allowable range of deviation from the class resolution, symmetric around the classresolution value. For PIV single fingerprint scanners with the class resolution of 500 ppi,the tolerance is 2%. For all scanners other than PIV, the tolerance is 1%.
A measurement of an objects surface geometry. Topographic data may be one, two, or three dimensional.
1D topography data is also known as a Linear Profile. A linear profile with n points shall be represented as a function of a single coordinate where at each point along a single axis (xi) (where i=1,...,n) there is a measured height (zi). Both xi and zi are measured in standard units (e.g., micrometers). An example of a linear profile is a cross-section through a striated toolmark (e.g., bullet land area); where xi is a spatial position measured in micrometers and zi is the corresponding height of the striation profile measured in micrometers.
2D topography data is also known as a Planar Image. An n-by-m planar image I shall be represented as a function of two coordinates where at each point (xi, yj) (where i=1,...,n; j=1,...,m) there is a measured surface color or intensity denoted I(xi, yj). An example of 2D topographic data is an image taken through a comparison microscope; where each point I (xi, yj) is the RGB (red, green, blue) color value measured at the specified (xi, yj) position. The measured color or intensity is a function of the surface geometry and the environmental conditions (e.g., light position). Although reference scales may be included in the collected image, the points (xi, yj) may or may not be measured in standard units (e.g., micrometers).
3D topography data is also known as a Heightmap. An n-by-m heightmap H shall be represented asa function of two coordinates where at each point (xi, yj) (where i=1,...,n; j=1,...,m) there is ameasured surface height zi,j = H(xi, yj). All three coordinates xi, yj, and zi,j are measured in standardunits (e.g., micrometers). The surface H is a 1-to-1 representation of the actual object. An exampleof 3D topographic data is a primer surface measured using a confocal microscope; where each pointH(xi, yj) represents the surface height (in micrometers) measured at the specified (xi, yj) position. 3Ddata captured on hardware compliant with ANSI/ASB Standard 061, Firearm and Toolmarks 3DMeasurement Systems and Measurement Quality Control can be used in virtual comparisonmicroscopy.
Physical layout or logical operation of a network
The branching structure of a phylogram
A fire scene where a fire continued to burn until most combustibles were consumed and the fire self-extinguished due to a lack of fuel or was extinguished when the fuel load was reduced by burning and there was sufficient suppression agent application to extinguish the fire.