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.
A chemical process of oxidation that occurs at a rate fast enough to produce heat and usually light in the form of either a glow or flame.
a usually rapid chemical process (as oxidation) that produces heat and usually light. Webster’s12
Noun - any substance that will burn, regardless of its autoignition temperature, or whether it is a solid, liquid or gas. Hawley’s11
Adjective - capable of undergoing combustion. NFPA 921, 3.3.32
Any finely divided solid material that is 420 microns or smaller in diameter (material passing a U.S. No. 40 Standard Sieve) and presents a fire or explosion hazard when dispersed and ignited in air.
An instrument that samples air and indicates whether there are ignitible vapors or gases present.
Any liquid that has a closed-cup flash point at or above 37.8C (100F). (See also 3.3.89, Flammable Liquid.)
see Ignitable Liquid
The heat, gases, volatilized liquids and solids, particulate matter, and ash generated by combustion.
the heat, gases, volatilized liquids and solids, particulate matter, and ash generated by combustion. NFPA 921, 3.3.36
DISCUSSION—Combustion products are the result of complete or incomplete combustion, but not thermal decomposition (see pyrolysis).
A simple file format for tabular data where individual values are separated by a comma (or other designated delimiter).
The intermixing of biological material representing multiple individuals.
Particles have compositions that are also commonly found in environmental particles from numerous sources. Discussion-When present in addition to particles that are characteristic of, or consistent with, GSR, or both, these particles can be of use in the interpretation of a population of particles and, consequently, the likelihood that that population is GSR. In isolation, however, such particles have little use in examinations for GSR.
Particles have compositions that are also commonly found in environmental particles from numerous sources. However, when present, in addition to particles that are characteristic of, and/or consistent with GSR, these particles can be of significance in the interpretation of a population of particles and, consequently, the likelihood that that population is GSR. In isolation, however, such particles have little significance in examinations for GSR
An algorithm that allows signals with a large dynamic range to be transmitted overfacilities with a smaller dynamic range. It is used in telephony (see -law and A-law)and some other types of communications
The process of examining two or more DNA data sets to assess the degree of similarity or difference.
The process of examining two or more DNA data sets to assess the degree of similarity or difference.
The process of examining two or more DNA data sets to assess the degree of similarity or difference.
A series of computational steps which seeks to assess both the level of geometric similarity (similarity of toolmarks) and the degree of certainty that the observed similarity results from a common origin. A comparison algorithm makes use of a scoring function or similarity score.
a system of two microscopes positioned side-by-side and connected via an optical bridge so that two specimens are examined simultaneously in a single field of view in either transmitted or reflected light.
a system of two microscopes positioned side-by-side and connected via an optical bridge so that two specimens are examined simultaneously in a single field of view in either transmitted or reflected light.
fire debris, (1) a sample of material collected from a fire scene which is, to the best of the collector’s knowledge, similar with respect to relevant characteristics to a sample suspected of containing ignitable substance, but which is not expected to contain an ignitable substance; (2) a sample of suspected ignitable substance submitted for the purpose of comparing with any ignitable substance separated from a debris sample.
DISCUSSION—A comparison sample should not be confused with a control sample. For example, a comparison sample might include unburned carpet or flooring that meets the requirements in (1).
DISCUSSION—Although, in theory, the use of comparison samples can help clarify the presence of a suspected inherent ignitable liquid, the presence of an ignitable liquid in a comparison sample does not necessarily mean it is inherent to the material.
Software that implements a comparison algorithm and may also include database, search, and visualization functionality.
Any variety of optical devices that can be placed in the light path of a polarized light microscope to introduce known, fixed or variable retardation in a specific vibration direction; the retardation and sign of elongation of the fiber can then be determined
any variety of optical devices that can be placed in the light path of a polarized light microscope to introduce known, fixed or variable retardation in a specific vibration direction; the retardation and sign of elongation of the fiber can then be determined.
A compensator (usually a plate of gypsum, selenite or quartz) that introduces a fixed retardation between 530 to 550 nm (approximately the retardation of the first order red color on the Michel-Lvy chart
a compensator (usually a plate of gypsum, selenite or quartz) that introduces a fixed retardation between 530 to 550nm (approximately the retardation of the first order red color on the Michel-Lvy chart).
A compensator (usually a mica plate) that introduces a fixed retardation between ~137147 nm (approximately the retardation of first-order gray on the Michel-Lvy chart)
a compensator (usually a mica plate) that introduces a fixed retardation between ~137147nm (approximately the retardation of first-order gray on the Michel-Lvy chart).
A wedge, usually cut from quartz, having continuously variable retardation extending over several orders (usually 3 to 7) of interference colors
a wedge, usually cut from quartz, having continuously variable retardation extending over several orders (usually3 to7) of interference colors.
a quarter-wave plate inserted above the specimen in the parallel 0 position with a calibrated rotating analyzer; measures low retardation and requires the use of monochromatic light.
A quarter-wave plate inserted above the specimen in the parallel 0 position with a calibrated rotating analyzer; measures low retardation and requires the use of monochromatic light
A compensator typically containing a plate of calcite or quartz, which can be tilted by means of a calibrated drum to introduce variable retardation
a compensator typically containing a plate of calcite or quartz, which can be tilted by means of a calibrated drum to introduce incrementally variable retardation.
Demonstrated and documented ability of an individual to perform assigned work in a discipline or subdiscipline, in accordance with a laboratory's technical procedures and training manuals, before the performance of independent casework.
The demonstration of technical skills and knowledge necessary to perform forensic DNA analysis successfully.
Demonstration that a forensic science practitioner has acquired and demonstrated specialized knowledge, skills, and abilities (KSAs) in the standard practices necessary to conduct examinations in a discipline or category of testing prior to performing independent casework
demonstration that a forensic science practitioner has acquired and demonstrated specialized knowledge, skills, and abilities (KSAs) in the standard practices necessary to conduct examinations in a discipline or category of testing prior to performing independent casework
demonstration that a forensic science practitioner has acquired and demonstrated specialized knowledge, skills, and abilities (KSAs) in the standard practices necessary to conduct examinations in a discipline or category of testing prior to performing independent casework
A person having suitable or sufficient skill, knowledge, and experience to train canines and canine handlers, who has demonstrated, through education, training, and operational experience, extensive skills and knowledge in the subject field or discipline. This person would normally perform the maintenance training and proficiency training in the field and may train canines in preparation for a formal course of instruction.
A person having suitable or sufficient skill, knowledge, and experience to train canines and canine handlers, who has demonstrated, through education, training, and operational experience, extensive skills and knowledge in the subject field or discipline. This person would normally perform the maintenance training and proficiency training in the field and may train canines in preparation for a formal course of instruction.
A person having suitable or sufficient skill, knowledge, and experience to train canines and canine handlers, who has demonstrated, through education, training, and operational experience, extensive skills and knowledge in the subject field or discipline. This person would normally perform the maintenance training and proficiency training in the field and may train canines in preparation for a formal course of instruction.
A person having suitable or sufficient skill, knowledge, experience to train canines and canine handlers.
A person having suitable or sufficient skill, knowledge, experience to train canines and canine handlers.
An ignition source that has sufficient energy and is capable of transferring that energy to the fuel long enough to raise the fuel to its ignition temperature. (See 19.4.2.)
A test designed to establish that an individual has demonstrated achievement of technical skills and met minimum standards of knowledge necessary to perform forensic DNA analysis.
A test used to demonstrate an individual's ability to successfully conduct an examination(s) prior toperforming casework.