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.
spheres composed of needles or rods all oriented perpendicular to the outer surface, or a plane section through such a sphere; a common form of polymer crystallization from melts or concentrated solutions.
shorter than course needles, but more substantial cross-section.
A training exercise in which two subjects walk the same pathway and then split into two different directions. When the canine is presented with a scent article from one of the subjects, the canine commences to trail and associate the correct person to the scent article. Despite the contamination of scent from the other person on the trail the canine is still able to discriminate between scents and identify the correct subject
A training exercise in which two subjects walk the same pathway and then split into two different directions. When the canine is presented with a scent article from one of the subjects, the canine commences to trail and associate the correct person to the scent article. Despite the contamination of scent from the other person on the trail the canine is still able to discriminate between scents and identify the correct subject.
A training exercise in which two subjects walk the same pathway and then split into two different directions. When the canine is presented with a scent article from one of the subjects, the canine commences to trail and associate the correct person to the scent article. Despite the contamination of scent from the other person on the trail the canine is still able to discriminate between scents and identify the correct subject
Loss, destruction, or material alteration of an object or document that is evidence or potential evidence in a legal proceeding by one who has the responsibility for its preservation.
the loss, destruction, or material alteration of an object or document that is evidence or potential evidence in a legal proceeding by one who has the responsibility for its preservation.
Discussion—Spoliation of evidence may occur when the movement, change or destruction of evidence, or alteration of the scene significantly impairs the opportunity of other interested parties to obtain the same evidentiary value from the evidence as did any prior investigator.
process whereby a material increases in temperature without drawing heat from its surroundings.
Discussion—Spontaneous heating is usually an exothermic oxidation reaction, which is frequently initiated by oxygen in air.
Initiation of combustion of a material by an internal chemical or biological reaction that has produced sufficient heat to ignite the material.
initiation of combustion of a material by an internal chemical or biological reaction that has produced sufficient heat to ignite the material; also known as spontaneous combustion.
The tendency of a behavior in a canine to reappear after it has undergone extinction.
in facial identification, the process by which an imposter intentionally attempts to be recognized as another person in a biometric system or intentionally attempts to be missed as an existing identity in the gallery.
a visible concentration of sample applied to the TLC plate; also known as the origin.
An analytes resistance to chemical change in a matrix under specific conditions for given time intervals
analyte’s resistance to chemical change in a matrix under specific conditions for given time intervals
a compound to prevent or slow down self-decomposition.
A location separate from the search site designated for canine handlers to wait until they are called to search.
An established or widely recognized model of authority or excellence as a reference point against which other things can be evaluated or the ideal in terms of which something can be judged.
An NFPA Standard, the main text of which contains only mandatory provisions using the word 'shall' to indicate requirements and that is in a form generally suitable for mandatory reference by another standard or code or for adoption into law. Nonmandatory provisions are not to be considered a part of the requirements of a standard and shall be located in an appendix, annex, footnote, informational note, or other means as permitted in the NFPA Manuals of Style. When used in a generic sense, such as in the phrase 'standards development process' or 'standards development activities,' the term 'standards' includes all NFPA Standards, including Codes, Standards, Recommended Practices, and Guides.
An NFPA Standard, the main text of which contains only mandatory provisions using the word 'shall' to indicate requirements and that is in a form generally suitable for mandatory reference by another standard or code or for adoption into law. Nonmandatory provisions are not to be considered a part of the requirements of a standard and shall be located in an appendix, annex, footnote, informational note, or other means as permitted in the NFPA Manual of Style. When used in a generic sense, such as in the phrase 'standards development process' or 'standards development activities,' the term 'standards' includes all NFPA Standards, including Codes, Standards, Recommended Practices, and Guides.
material of established origin with certified properties.
material of established origin with certified properties.
Discussion—For the purposes of fire debris analysis, this term is used for materials with a certificate of analysis from the supplier reporting the results of their characterization.
in video analysis, the transformation of one television system signal to another, for example, National Television System Committee (NTSC) to Phase Alternating Line (PAL).
Investigator's tools and equipment that every investigator must carry.
a method published by a recognized international, regional, or national standard development organization (for example, ASTM, ASB, AOAC, etc.).
Written documentation maintained by the laboratory including laboratory policies, technical protocols and methods for specific forensic analyses (see also technical procedure).
Written analytical procedure that describes how to perform certain organization activities
natural fibers or cut lengths from filaments.
a 5-bit binary sequence, or equivalent ASCII character, used to signify the beginning of track data. (See ISO/IEC 7813:2006.)
A largely unconscious defensive response to sudden or threatening stimuli or perceived stimuli.
A largely unconscious defensive response in a canine to sudden or threatening stimuli or perceived stimuli.
see static headspace sampling (E1388), and static headspace concentration (E3189).
an extraction technique in which a portion of the headspace vapors is removed from the sample container.
an extraction technique in which a portion of the headspace vapors is removed from the sample container and concentrated onto an adsorbent medium.
an extraction technique in which a portion of the headspace vapors is removed from the sample container and concentrated onto an adsorbent medium.
an extraction technique in which a portion of the headspace vapors is removed from the sample container.
the solid adsorbent coating layer of a TLC plate.
The probability of obtaining the observed resultor a more exaggerated oneif the null hypothesis of no effect was true.
A Category 2 scoring function.
a microscope containing two separate optical paths, one for each eye, giving a three-dimensional view of a specimen.
The act of producing a snoring sound.
The act of producing a snoring sound [1].
A friction ridge image created by combining images that were separately captured.
1) Chance, or random variation 2) in DNA testing, refers to random sampling error from extracts containing low levels of DNA and/or random variation in selection of alleles amplified at a particular locus.
Changes in a DNA profile that generally occur when suboptimal or limiting quantities of DNA are tested. This may be due to sampling variation (e.g., pipetting) of the target DNA that goes into the ANSI/ASB Standard 020, 1st Ed. 2018 2 polymerase chain reaction (PCR) and/or random events between primers and target DNA during PCR amplification. The effects may be observed at one or more loci, and include: 1) peak height imbalance of sister alleles in a heterozygous pair; 2) loss of data (referred to as 'allele drop out' when one or more alleles are missing at a locus and 'locus drop out' when all alleles are missing from a locus); 3) allele drop-in (allelic peak(s) in an electropherogram that are not reproducible); and 4) elevated stutter peaks