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.
To release the firing pin on an unloaded chamber of a firearm.
an organic liquid that, when applied as a thin film, readily absorbs oxygen from the air and polymerizes to form a tough, elastic film.
Discussion—Some examples of drying oils include linseed, tung, and soybean oils. Drying oils are prone to spontaneous heating when exposed to air.
An impression formed when the substrate, materials being transferred, and the outsole or tire treadare dry (e.g. footwear impressions in dust).
The propensity of a canine to exhibit instinctual behaviors when faced with particular stimuli. Drives are triggered by these particular stimuli (e.g., food or retrieve) and expressed in a typical and predictable way that is associated with the particular stimulus. Expression of drives can be enhanced or diminished through experience (e.g., training, environment, etc.), but they cannot be created or eliminated. Drive therefore reflects the motivation to perform a behavior.
The propensity of a canine to exhibit instinctual behaviors when faced with particular stimuli. Drives are triggered by these particular stimuli (e.g., food or retrieve) and expressed in a typical and predictable way that is associated with the particular stimulus. Drives can be enhanced or diminished through experience (e.g., training, environment, etc.), but they cannot be created or eliminated. Traditionally defined in the working canine literature as an exaggerated, instinctual response to certain stimuli and situations. Drive is most narrowly and clearly defined as a willingness, vigor, or enthusiasm to engage in certain behavior, contexts, or situations. (See food drive, rank drive, retrieve drive, and survival drive)
The spread of fire by the dropping or falling of burning materials. Synonymous with 'fall down.'
Ordinate values within a dataset that did not receive enough signal during the measurement for aheight measurement to be acquired. These are often represented as NaN, zero, blank, or theminimum measured value.
When an individual is victimized while mentally or physically incapacitated due to the effects of ethanol and/or other drugs.
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.
A canine trained in two disciplines. For example, a canine trained for narcotics and criminal apprehension.
A canine trained in two disciplines. For example, a canine trained for narcotics and criminal apprehension.
A cartridge that does not contain primer, propellant, or explosive charge and therefore cannot befired.
A cartridge that does not contain primer, propellant, or explosive charge and therefore cannot be fired
soluble substances that add color to textiles.
Discussion—Dyes are classified into groups that have similar chemical characteristics (for example, aniline, acid, and azo) and also by their method of application (for example, reactive or direct). They are incorporated into the fiber by chemical reaction, absorption, or dispersion.
the removal of the dye from a fiber by incubating the fiber(s) in an appropriate solvent.
see dynamic headspace concentration.
see dynamic headspace concentration.
an extraction technique in which a portion of the headspace vapors is exchanged from the sample container and concentrated onto an adsorbent medium through applied positive or negative pressure.
an extraction technique in which a portion of the headspace vapors is exchanged from the sample container and concentrated onto an adsorbent medium through applied positive or negative pressure.
(1) in image analysis, the difference between the brightest highlight and darkest value that a sensor can detect and record in a single image; (2) in audio and video analysis, the ratio of the strongest (undistorted) signal to that of the weakest (discernible) signal in a unit or system as expressed in decibels (dB); (3) a way of stating the maximum signal-to-noise ratio.
a general term given to a class of explosives in which the principal organic energetic material is usually NG and/or EGDN; or other explosive oils.
Discussion—(1) Usually inorganic oxidizers such as nitrate salts and plant material are also included. (2) It should be noted that this does not describe "military" type dynamites.
This stands for two separate application profiles of the ANSI/NIST-ITL standard:a) Acronym for the FBI's application profile of the ANSI/NIST-ITL standard:Electronic Biometric Transmission Specification.b) Acronym for the US Department of Defense's application profile of theANSI/NIST-ITL standard: Electronic Biometric TransmissionSpecification.
An instrument that uses an electrostatic charge along with toner distribution as the mechanism to visualize paper fiber disturbances (for example, indentations and erasures).
Extended Feature Set for markup of friction ridge data [2015a>]as defined in fields9.300-9.399 [
Temperatures reached in fires that produce physical effects that can be related to specific temperature ranges.
any paint pigment that is designed to produce a significant change in color attribute(s) in a paint film when the film is viewed or illuminated from varied angles.
The FBI's earlier application profile of the ANSI/NIST-ITL standard: Electronic FingerprintTransmission Specification. It has been superseded by EBTS.
a material that can be deformed but when the forces are removed it returns to its original form. Serves as the base material for pressure sensitive adhesives.
the polymeric backbone of a pressure sensitive adhesive imparting elastic properties, for example, rubber.
A disease of the elbow joint of canines caused by growth disturbances in the elbow joint.
A disease of the elbow joint of canines caused by growth disturbances in the elbow joint.
a device, designed and used for the electrical ignition of fireworks and pyrotechnic articles, that contains a small amount of pyrotechnic material, which ignites when a specified electric current flows through the leads.
Discussion—An electric current is passed through the bridgewire, using a wire circuit, and a temperature rise occurs in the bridgewire that ignites a small dab of match composition. A burst of flame is produced that ignites a section of fuse or a charge of pyrotechnic composition.
A small, incandescent particle created by some arcs.
a small tube or block containing a small quantity of ignition composition in contact with a wire bridge.
The complete longitudinal electronic dental history of an individual
A broad concept that includes public or private information stored in an electronic or digital medium, such as data available from computers (including email), CD-ROM discs, DVDs, Internet, cloud storage, personal digital assistants (PDAs), smart phones, tablets, GPS systems, satellites, and drones. ESI includes writings, drawings, graphs, charts, photographs, sound recordings, images, video recordings, data compilations, computer-aided design files such as blueprints or maps, metadata, equipment/process control and data logging system files, and any other data that is stored electronically.
A plot of fluorescence units over time showing the measured peaks of a DNA molecule atvarious genetic locations.
A technique used in laboratories to separate macromolecules based on size and charge. Negatively charged molecules (e.g. DNA and RNA) migrate towards a positively charged pole through a sieving matrix, which permits a size-dependent separation.
The examination of (writing) indentations of paper.
An instrument that uses electrostatic charge as the mechanism to visualize paper fiber disturbances (for example, indentations, erasures, typewritten material/lift off).