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.
thick tablets having nearly equal width, breadth and thickness.
A group of citizens empaneled to investigate potential criminal conduct and/or determine whether probable cause exists to charge someone with a crime.
parallel set of linear, regularly repeating grooves that, when illuminated, produces dispersion of light into its requisite wavelengths with maxima and minima of light intensity as a consequence of interference.
Discussion—These maxima and minima vary in position with wavelength. This allows radiation of any given wavelength to be isolated from a mixture of wavelengths (for example, white light) and allows the grating to be used as part of a monochromator. The dispersion or ability to resolve separate wavelengths is expressed as the number of lines (or steps) in the grating per millimetre.
an image encoded with a single channel or component.
operation that modifies a single channel or component of image data (for example, a single color).
Ranges from an untrained canine up to but not including a certified canine. (See novice dog.)
A type of systematic pattern used to ensure thorough coverage of a defined area.
Visual (macroscopic) assessment of skeletal and dental materials.
A conducting connection, whether intentional or accidental, between an electrical circuit or equipment and earth or to some conducting body that serves in place of the earth.
A current that flows outside the normal circuit path, such as (1) through the equipment grounding conductor; (2) through conductive material in contact with lower potential (such as earth), other than the electrical system ground (metal water or plumbing pipes, etc.); or (3) through a combination of these ground return paths.
A document that is advisory or informative in nature and that contains only nonmandatory provisions. A guide may contain mandatory statements such as when a guide can be used, but the document as a whole is not suitable for adoption into law.
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; a combination of alleles or 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 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 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.