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.
An individual who performs medicolegal death investigations.
The medicolegal investigation includes the collection of data, photographs, evidence, witness interviews, external examination of the body at the scene, and other forensic information and analysis that will contribute to the identification of decedent, determination of cause and manner of death, reconstruction of the accident or crime scene, and support the provision of survivability factors.
Relevant to the medicolegal death investigation system; anthropologically, this term typically refers to human skeletal material of recent origin.
the core of the hair shaft that is composed of vacuoles and cells that can be air- or fluid-filled.
Discussion—The medulla (if present) occurs in a continuous, discontinuous, or fragmented pattern along the length of a hair and appears translucent or opaque.
the central portion of a hair composed of a series of discrete cells or an amorphous spongy mass.
Discussion—The medulla can be air-filled, and if so, appears opaque or black using transmitted light or white using reflected light. In animal hair, several types have been defined: uniserial or multiserial ladder, cellular or vacuolated, and lattice.
in computer forensics, (1) hardware used for the temporary storage of operating instructions and data while a digital device is running, and (2) see random access memory.
in computer forensics, the modification of data by a running system during the memory acquisition process.
The level of awareness and response to the environment.
The level of awareness and response to the environment.
Documentation relevant to the biometric data, but not the biometric data itself.Metadata may include both signal/sample-related and content-related information.Examples are the format of the data file, such as WAV and the scope of accreditation ofa DNA processing laboratory.
data, frequently embedded within a file, that describes a file or directory.
two or more samples that appear to have the same color under one type of illumination but can appear dissimilar under different lighting conditions, or two or more samples that appear to be the same color under all lighting conditions, yet their reflectance/transmittance spectral curves are different.
when colors are perceived to be matching despite having different spectral profiles.
Discussion—These spectral differences often become apparent under different illumination conditions.
A combination of procedural steps used to perform a specific technical process. The method includes the validated steps, reagents, and critical instruments needed to perform the process or portion of a process. The same method may be conducted using different equipment (automated vs manual) when appropriately validated.1
A quantitative procedure by which a known concentration of the target analyte is added to multiple aliquots of the case sample(s)
Methodology refers to the categories of methods used to perform a stage of a DNA typing technology or technologies. For example, methodologies for STR technology can include extraction, quantification, amplification, and detection.
An estimate based on measurement of skeletal elements.
Property of a measurement result whereby the result can be related to a reference through a documented unbroken chain of calibrations, each contributing to the measurement uncertainty.
Property of a measurement result whereby the result can be related to a reference through a documented unbroken chain of calibrations, each contributing to the measurement uncertainty
property of a measurement result whereby the result can be related to a reference through a documented unbroken chain of comparisons, each contributing to the measurement uncertainty (see 2.4.1 of International Vocabulary of Metrology (VIM) Basic and General Concepts and Associated Terms [10]).
Military Grid Reference System
a chart relating thickness, birefringence, and retardation so that any one of these variables can be determined when the other two are known.
the decomposition of petroleum products in fire debris by bacterial action that can diminish some compounds, resulting in an altered pattern in a chromatogram.
An implant that is placed under the skin of an animal that provides a unique electronic identification.
An implant that is placed under the skin of an animal that provides a unique electronic identification.
a small drop of liquid that would fit on the end of a standard size, flattened toothpick; the approximate volume of this drop would be 10 to 25 µL.
a term that describes characteristics too small to be resolved by the unaided eye, but large enough to be resolved with a microscope.
concerning a microscope or the use of a microscope.
A specialized spectrophotometer designed to measure the absorbance, reflectance and emission spectra of microscopic areas on samples.
sample preparation approach that sequentially passes a blade at a shallow depth through a sample resulting in sections of selected thickness as well as a flat block.
a sample preparation method that sequentially passes a blade at a shallow depth through a specimen, resulting in sections of selected thickness.
pertaining to the IR region of the electromagnetic spectrum with wavelength range from approximately 2.5 to 25 µm (wavenumber range approximately 4000 to 400 cm-1).
the movement over a period of time of an ingredient from one layer to another.
Discussion—This often occurs in electrical tapes where plasticizer in the polyvinyl chloride (PVC) backing "migrates" into the adhesive.
Minute (of time)
a naturally occurring inorganic element or compound having an orderly internal structure and characteristic chemical composition, crystal form(s), and physical properties, or an element or chemical compound that is crystalline and that has formed as a result of geological or pedogenic (soil-formed) processes.
Discussion—Artificial and biogenic crystalline materials are not minerals but can occur in geological materials (for example, cement powder, lime, lye, biogenic calcite, biogenic hydroxyapatite, bricks) and can be detected by XRD.
The minimum concentration of a combustible dust cloud that is capable of propagating a deflagration through a uniform mixture of the dust and air under the specified conditions of test. [68, 2018]
Lowest number of points, including a chromatographic separation, that must be achieved within a testing regimen to identify an analyte in a specific matrix.
The lowest capacitive spark energy capable of igniting the most ignition-sensitive concentration of a flammable vapor-air mixture or a combustible dust-air mixture as determined by a standard test procedure. [652, 2019]
A minimum estimate of the number of individuals represented by a sample; calculated as the number of the most repeated element after sorting by element, side, and developmental status.
Written documents established to define the least level of performance considered acceptable.
The point where a friction ridge terminates, or splits into two or more ridges. A subset of the friction ridge detail/features traditionally consisting of ridge endings, bifurcations, and dots used to compare and interpret similarity and dissimilarity between two impressions.
The point where a friction ridge terminates, or splits into two or more ridges. A subset of the friction ridge detail/features traditionally consisting of ridge endings, bifurcations, and dots used to compare and interpret similarity and dissimilarity between two impressions.
The point where a friction ridge begins, terminates, or splits into two or more ridges.Minutiae are friction ridge characteristics that are used to individualize a friction ridgeimage (fingerprint, palm print, plantar). This is also known as Level 2 detail.
The point where a friction ridge terminates, or splits into two or more ridges. A subset of the friction ridge detail/features traditionally consisting of ridge endings, bifurcations, and dots, or any combination thereof, used to compare and interpret similarity and dissimilarity between two impressions.
When the canine fails to alert in the known presence of the target odor/scent.
Performance demanded of a person or canine team in accordance with certain fixed regulations, needs of the department or agency. Compulsory pre-requisites needed before deployment.
Performance demanded of a person or canine team in accordance with certain fixed regulations, needs of the department or agency. Compulsory pre-requisites needed before deployment.