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.
Recommended practice that allows some discretion or leeway in its interpretation, implementation, or use. A set of general principles used to provide direction and parameters for decision making.
a generic term used for propellant powders used in firearms.
residues formed during the discharge of a firearm.
the external morphology of the crystal.
The lessening or disappearance of a response that was once elicited by the stimulus with repeated presentation of the same or closely related stimulus.
a fibrous outgrowth from the skin of mammals.
an invagination of the epidermis which contains the root of the hair.
A stamp that requires a separate ink pad when making impressions.
The handler is a person who has successfully completed a documented training and certification process in canine handling in the specific discipline of ignitible liquid canine detection and maintains those abilities through field application, maintenance training, scheduled recertification, and continuing education. (See 3.4.2, Certification.) [SC1, 2011].
See canine handler.
Any action or cue made by the handler that causes the canine to perform incorrectly. (See canine handler error.)
Any action or cue made by the handler that causes the canine to perform incorrectly. (See 3.13 canine handler error.)
Any action or cue made by the handler that causes the canine to perform incorrectly. (See canine handler error.)
Any action or cue made by the handler that causes the canine to perform incorrectly. (See 3.13 canine handler error.)
A group of similar haplotypes that share a common ancestor with a single-nucleotide polymorphism mutation.
A set of linked DNA variations, or polymorphisms, that tend to be inherited together (e.g., commonly used for human Y-chromosome or mitochondrial analysis). A haplotype can refer to a combination of alleles or to a set of single nucleotide polymorphisms (SNPs) found on the same chromosome.
A set of linked DNA variations, or polymorphisms, that tend to be inherited together (e.g. commonly used for mitochondrial or Y-chromosome analysis). A haplotype can refer to a combination of alleles or to a set of single nucleotide polymorphisms (SNPs) found on the same chromosome.
A set of linked DNA variations, or polymorphisms, that tend to be inherited together; a combination of alleles or a set of single nucleotide polymorphisms (SNPs) found on the same chromosome.
A state in which allele and single locus genotype frequencies do not change (on average) from one generation to the next in a population. When alleles in a population are independent, allele and genotype frequencies are related through the Hardy-Weinberg principle: for a locus with 2 alleles P and Q at frequencies of p and q, homozygotes for P are found at frequency p2, homozygotes for Q are found at a frequency of q2, and heterozygotes are found at a frequency of 2pq. Use of the theta correction removes the need to assume Hardy-Weinberg equilibrium in the population for which a frequency database is constructed.
a string of numerical values used to substantiate the integrity of digital evidence or for inclusion/exclusion comparisons against known value sets or both.
an established mathematical calculation that generates a numerical value based on input data.
A quick search or rapid assessment of the defined area.
A condition that presents the potential for harm or damage to people, property, or the environment.
A substance (solid, liquid, or gas) that when released is capable of creating harm to people, the environment, and property.
Any material that is an air-reactive material, flammable or combustible liquid, flammable gas, corrosive material, explosive material, organic peroxide, oxidizing material, radioactive material, toxic material, unstable material, biological material or water-reactive material, and any substance or mixture of substances that is an irritant or a strong sensitizer or that generates pressure through exposure to heat, decomposition, or other means.
the space above a material that includes the vapors produced by the liquid or solid material.
practice for sampling and analyzing the headspace in a closed container.
Discussion—In fire debris analysis, there are several types of headspace sampling techniques.
The vapor surrounding a specific source of interest or investigation.
A form of energy characterized by vibration of molecules and capable of initiating and supporting chemical changes and changes of state.
An arrow used in a fire scene drawing to show the direction of heat, smoke, or flame flow.
The measure of the rate of heat transfer to a surface, expressed in kilowatts/m2, kilojoules/m2 sec, or Btu/ft2 sec.
The heat energy that brings about ignition.
The rate at which heat energy is generated by burning.
The exchange of thermal energy between materials through conduction, convection, and/or radiation.
The exchange of thermal energy between materials through conduction, convection, and/or radiation.
A three-dimensional topographic data set consisting of surface points (x, y, z) where each dimension is a coordinate measured in standard units (e.g., micrometers). See 3.14 topography data.
The study of blood in health and disease.
The study of blood in health and disease.
The presence of more than one mitochondrial DNA (mtDNA) sequence or type within a single individual.
The presence of more than one mitochondrial DNA (mtDNA) sequence or type within a single individual.
The presence of more than one mitochondrial DNA (mtDNA) sequence of type within a single individual.
The presence of more than one mitochondrial DNA sequence or type within a single individual.
In computer forensics, a sector in the current configuration of a drive that cannot be accessed by read and write commands without changing the drive configuration.
Discussion—Sectors in a host protected area would be hidden data sectors.
A material that is capable of sustaining a reaction front that moves through the unreacted material at a speed equal to or greater than that of sound in that medium [typically 1000 m/sec (3000 ft/sec)]; a material capable of sustaining a detonation. (See also detonation.)
energetic materials that support a supersonic detonation wave, irrespective of the ambient condition of confinement; sometimes abbreviated HE.
descriptive of an explosive that undergoes complete reaction (or detonation) of the material as designed.
An impression with observed data that are unambiguous and self-evident due to high clarity and quantity.
In this document, it refers to a MS instrument that can give at least 10,000 nominal mass resolving power at full width of the peak at half its maximum height (FWHM) for the compound of interest.
A rapid pressure rise or high-force explosion characterized by a shattering effect on the confining structure or container and long missile distances.
An abnormal formation of the hip socket.