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.
Any product that prevents substrate material from adhering to the cast.
an inert material with a low surface energy, applied to a backing film on the side opposite the adhesive, that provides ease of unwind and prevents delamination or tearing.
a coating applied to the top side of the backing that provides ease of unwind and prevents delamination or tearing.
set of items (or sources of items) which in the examiner’s judgement best reflects a proposition and the circumstances of the case
Note 1 to entry: See ISO 21043-4:2025, Annex C for examples of relevant population.
The extent to which an experiment, test or measuring procedure yields the same results on repeated trials. Low probability of alerting to anything other than a target odor/scent and a high probability of alerting to a target odor/scent. Evidence that establishes a fair probability that a target odor/scent is present. The extent to which a measurement is repeatable and consistent and free from random errors. (See consistency.)
Checking beyond the functional aspects to measure the reliability of the software in the laboratory environment. This includes testing the impact on software performance when utilized by multiuser or multi-site scenarios and verifying network, server, and other applicable resources can handle the application's needs.
Credibility and trustworthiness of proffered evidence.
Consistency of results as demonstrated by reproducibility or repeatability.
Results that are repeatable when applied as designed.
contrast between a particle or crystal and its media due to the difference between their refractive indices. The greater the numerical difference in refractive indices, the greater the relief.
Training to work the canine at a distance from the canine handler. A training situation in which an attempt is made to remove the human element from the picture.
Extent of agreement between more than one result determined in the same place, by the same person, on the same equipment, in the same way, at similar times.
Also referenced in ASTM E1732 Standard Terminology Relating to Forensic Science, ASTM E177-14 Standard Practice for Use of the Terms Precision and Bias in ASTM Test Methods.
Measurement precision under a set of conditions that includes the same measurement procedure, same operators, same measuring system, same operating conditions, same location, and replicate measurements on the same or similar objects over a short period of time
conditions where independent test results are obtained with the same method on identical test items in the same laboratory by the same operator using the same equipment within short intervals of time.
Experiments performed to verify the results of the assay by the same personnel and/or applicable instrumentation.
In disaster applications, three or more barks directed at the same victim that may be interspersed with digging, scratching, or any other attempt to access the victim. The canine may reposition itself while indicating at target location.
See "Reproducibility"
independent analysis of at least two samples taken from the same original item
Communication of outcomes of the forensic process.
EXAMPLE: Observations, findings, interpretations, conclusions and/or opinions.
any sound effect produced by an explosion.
range of concentrations that can be reliably measured by an analytical procedure that will be reported per the Program’s specifications
Extent of agreement between repeated results determined under any combination of different conditions.
Also referenced in ANSI/ASB Technical Report 025, Crime Scene/Death Investigation - Dogs and Sensors - Terms and Definitions, ASTM E1732 Standard Terminology Relating to Forensic Science, ASTM E177-14 Standard Practice for Use of the Terms Precision and Bias in ASTM Test Methods.
Measurement precision under a set of conditions that includes different locations, operators, measuring system, and replicate measurements on the same or similar objects
conditions where test results are obtained with the same method on identical test items in different laboratories with different operators using different equipment.
Experiments performed to assess the capability to obtain the same test results when an experiment is repeated between different operators and/or detection instruments.
Fundamental knowledge one must have in order to perform a specific task.
The essential skills one must have in order to perform a specific task.
changing the size and/or resolution of the image by adding or subtracting pixels through interpolation.
Odor/scent that originated from any substance/subject that may or may not be physically recoverable or detectable by other means. The odor/scent that originated from a target substance/subject and lingers after the target substance/subject has been removed or has totally decomposed (as in the case of human remains).
Scent that originated from any subject that may or may not be physically recoverable or detectable by other means. The scent that originated from a target subject and lingers after the target subject has been removed or has totally decomposed (as in the case of human remains).
Scent that originated from any subject that may or may not be physically recoverable or detectable by other means. The scent that originated from a target subject and lingers after the target subject has been removed or has totally decomposed (as in the case of human remains).
Scent that originated from any subject that may or may not be physically recoverable or detectable by other means. The scent that originated from a target subject and lingers after the target subject has been removed or has totally decomposed (as in the case of human remains).
Remnants of a target substance that can be recovered and identified.
in computer forensics, (1) data that are contained in unallocated space or file slack; (2) data left in storage after information processing operations are complete, but before degaussing or overwriting has taken place.
changing the size of an image by changing the number of pixels per unit of measurement without adding or subtracting any pixels from the image.
in facial identification, image, and video analysis, a measure of the limit of an image or display to distinguish between two separate but adjacent stimuli, such as elements of spatial detail in an image, or similar colors.
the act, process, or capability of distinguishing between two separate but adjacent parts or stimuli, such as elements of detail in an image, or similar colors.
the ability to visually separate two bands.
Related to breathing and exchange of oxygen and carbon dioxide.
Related to breathing and exchange of oxygen and carbon dioxide.
A behavior that a canine has been trained to exhibit upon locating the source of a target odor/scent. This behavior may be either passive (sit, stare, down, point) or active (bite, bark, scratch, jump, etc.). (See indication.)
A behavior that a canine has been trained to exhibit upon locating the source of a target odor/scent. This behavior may be either passive (sit, stare, down, point) or active (bite, bark, scratch, jump, etc.).
The accountability of a person or other entity for the event or sequence of events that caused the fire or explosion, spread of the fire, bodily injuries, loss of life, or property damage.
(1) in computer forensics, the process of restoring data from an image, and (2) in image and video analysis, any process applied to an image that has been degraded by a known cause (for example, defocus or motion blur) to remove partially or totally the effects of that degradation.
The product of the forensic service provider. This term is broad and includes observations, data, calculations, interpretations, and opinions.
Also referenced in ANSI/ASB 167 Standard for Reporting Results from Friction Ridge Examinations
the actual distance between two doubly refracted rays as they emerge from an anisotropic fiber; dependent upon the difference in the two refractive indices, |n||n|, and the thickness of the fiber.
the ratio of the distance traveled by the solute band's center divided by the distance traveled by the solvent front, both measured from the origin.
Behaviors associated with finding and returning prey or objects back to the canine handler or social group.