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.
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.
A person or organization that can affect, be affected by, or perceive itself to be affected by a decision or activity.
The product of direct physical contact of an item, such as a stamping device, resulting in transfer of the characteristics of that item onto the substrate.
A hand-marking device capable of making an inked impression using a variety of die materials that include, but are not limited to, vulcanized rubber, laserable rubber, photopolymer, gel, and metal. Synonyms: hand stamp, self-inking stamp, pre-inked stamp, flat-die, cachet.
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.
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 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.
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.
material of established origin with certified properties.
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.
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
a method published by a recognized international, regional, or national standard development organization (for example, ASTM, ASB, AOAC, etc.).
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 in a canine to sudden or threatening stimuli or perceived stimuli.
A largely unconscious defensive response 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.
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 quantitative statement that provides a measure of support for the comparison performed (e.g., random match probability, likelihood ratio).
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 [1].
The act of producing a snoring sound.
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.
Describes 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 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 (a non-allelic peak in the stutter position exceeding the stutter expectation of the laboratory).
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
Changes in a DNA profile that generally occur when suboptimal or limiting quantities of DNA are tested.
NOTE This may be due to sampling variation (e.g., pipetting) of the target DNA that goes into the 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 (a non-allelic peak in the stutter position exceeding the stutter expectation of the laboratory).
The peak height value in a DNA electrophoretic profile above which it is reasonable to assume that, at a given locus, allelic drop out of a sister allele in a heterozygous pair has not occurred in a single source DNA sample; due to the possibility of shared alleles in mixed samples, the presence of allele peaks above the stochastic threshold is no guarantee that allele drop out did not occur in mixed DNA sample profiles.
in computer forensics, retrievable retention of data; electronic, electrostatic, or electrical hardware or other media into which data may be entered, and from which data may be retrieved.