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.
a homogeneous, solid body of a chemical element or compound, having a regularly repeating atomic arrangement that can be outwardly expressed by plane faces.
the three-dimensional regularly repeating set of points that represent the translational periodicity of a crystal structure.
Discussion—Each lattice point has identical surroundings. Lattice is the abstract pattern used to describe the internal geometric structure of crystals. Lattice and structure are not synonymous, as structure refers to the real mineral material.
having a crystal structure or a regular arrangement of atoms in a crystal lattice.
Perception of the near infallibility of forensic science in response to popular media.
Computerized tomography scan.
A verbal or physical action (done consciously or unconsciously) by anyone, and/or any environmental stimulus that causes a detector canine to change its actions to respond to an area or item whether target odor/scent is present or not.
An assemblage of biological reference materials acquired and maintained with associated data according to explicit quality control standards.
the temperature at which a ferromagnetic metal loses its ferromagnetic properties.
A flow of electric charge.
Data for the individual in his/her current state, not necessarily data recorded or createdon the current date. For instance, current data on a subject may be a radiograph of adecedent taken at the time of burial several years ago that is now being compared toradiographs that had been provided for a missing person prior to the assumed date ofdeath of the subject.
Client, authority, organization, or person(s) requesting the forensic services.
the outermost region of a hair composed of layers of overlapping scales.
Discussion—The dimension of the cuticle as measured from its outer margin to the cortex is often described in relative terms (for example, thin, medium, thick).
in mammalian hair fibers, the layers of flattened cells enclosing the cortex, which form an envelope of overlapping scales surrounding the fiber.
a cuticle with linear breaks that are perpendicular to the length of the shaft.
a feature in which the distal edges of the cuticular scales are curved away from or cupped toward the hair shaft.
a cuticle in which the outer margin has a notched appearance like a saw blade.
Cycle number (in quantitative PCR) at which the fluorescence generated within a reaction exceeds a defined threshold; this value is converted to a DNA concentration for each sample tested using a standard curve developed from DNA samples of known concentrations.
a subclass of aliphatic hydrocarbons with the general formula CnH2n , where the chain of constituent carbon atoms connects to produce a ring structure (with or without side chains) containing only single bonds; also known as cycloparaffin or, historically, naphthene.
Discussion—Naphthenes should not be confused with the term "naphthalenes" which can be used to refer to a subclass of polyaromatic hydrocarbons which is based on naphthalene.
The circular gray-to-black deposit around the front margin of the chamber(s) of a revolvercomposed of gunshot residues deposited during the firing process. Also known as a smoke ring,halo, or simply flare.
in diffraction of X-rays by a crystal, the distance or separation between successive and identical parallel planes in the crystal lattice; d-spacing is expressed as d in the Bragg equation.
information in analog or digital form that can be transmitted or processed.
quantitative or qualitative representation that is observed, measured, collected, or gathered that characterizes some static or dynamic attribute of the physical world or the use of it by individuals or groups of people and that is suitable for communication, interpretation, or processing by humans or machinesg
g: ASTM E867-06 (2020) Standard Terminology Relating to Vehicle Pavement Systems available from ANSI.
The process of systematically utilizing logical techniques to dissect, reorder, evaluate, and interpret data.
a file consisting of stored data (that is, text, numbers, graphics, etc.) as compared to a program file of commands and instructions for a digital device.
A reference point or an approximation of the Earth's surface against which positional measurements are made for computing locations. Horizontal datums are used for describing a point on the Earth's surface, in latitude and longitude or other recognized coordinate systems.
the time (expressed as a percentage of real time) during which the energy dispersive X-ray spectrometer is not able to process X-rays.
The removal or loss of an amine group from a base, which can result in incorrect pairing during DNA amplification.
A permanent document, registered with the vital records office, that states the identification, fact of death, cause of death, and manner of death; a source of mortality statistics.
Location or site at which a death is pronounced, and at which the decedent’s body is located. This need not be the same location as the incident scene.
to restore an image by attempting to reverse degradation caused by blur.
the ruins or rubble which results from the burning of materials. (See also fire debris.)
Deceased person or any suspected human remains.
An administratively defined cutoff or concentration that is at or above the methods limit of detection or limit of quantitation and is used to discriminate between positive and negative results.
An administratively defined cutoff or concentration that is at or above the method's limit of detection or limit of quantitation and is used to discriminate between positive and negative results.
Administratively defined cutoff or concentration that is at or above the method’s limit of detection or lower limit of quantitation and is used to discriminate between a negative and positive test result.
An administratively defined cutoff or concentration that is at or above the methods limit of detection or limit of quantitation and is used to discriminate between positive and negative results.
rule that describes how measurement uncertainty is accounted for when stating conformity with aspecified requirement.
First-party attestation.
Fluids associated with the human body decay process that produces a distinctive odor.
alteration in the root or the proximal end of a hair that can include discoloration, postmortem root banding, or a tapered or brush-like appearance, as well as fungal tunneling along the length of the shaft.
The decoy should always be under the control of the canine trainer for the exercise. The canine trainer will tell the decoy how he/she is to behave throughout the training exercise, while in the presence of the canine(s) being trained. Given the proper equipment, the decoy will manipulate the canine's behavior according to the canine trainer through agitation, body movement (toward, away from and perpendicular to the canine's position), posture, noises, etc. The decoy may also provide the canine with a bite, by presenting a part of the body.
A training term, most commonly associated with patrol work but the term can be used in other canine training disciplines. A person will perform the role as a decoy. Multiple people can be used if more than one decoy is needed for the training exercise. (See distractor.)
The decoy should always be under the control of the canine trainer for the exercise. The canine trainer will tell the decoy how he/she is to behave throughout the training exercise, while in the presence of the canine(s) being trained. Given the proper equipment, the decoy will manipulate the canine's behavior according to the canine trainer through agitation, body movement (toward, away from and perpendicular to the canine's position), posture, noises, etc. The decoy may also present themselves for apprehension by the canine.
The process by which conclusions are drawn by logical inference from given premises.
Behavior exhibited by canines to protect themselves and, or their canine handler when faced with a perceived or real threat.
Behaviors indicating that the dog will not attack unless the stimulus eliciting the behavior does not withdraw (typically rooted in fear and characterized by backward and lowered body language and threatening postures intended to protect the dog's body, (e.g., tucked tail).
Propagation of a combustion zone at a velocity that is less than the speed of sound in the unreacted medium. [68, 2018]
propagation of a combustion zone at a velocity that is less than the speed of sound in the unreacted medium.
The fragmenting, or breakdown, of DNA by chemical, physical, or biological means.