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.
The intentional act to prevent damage, contamination, alteration, or deterioration of anything contained within a scene.
Application or use of measures to prevent damage, change or alteration, or deterioration.
in computer forensics, a process undertaken to maintain the integrity of potential digital evidence.
a viscoelastic material which, in solvent-free form, remains tacky and will adhere instantaneously to most solid surfaces with the application of very slight pressure.
an adhesive that consists of a polymeric base, usually with appropriate plasticizers and tackifiers. It can form an adhesive bond with no physical or chemical change and with the application of only slight pressure.
a combination of a pressure sensitive adhesive with a continuous flexible backing (for example, cloth, paper, metal, or plastic) or with a backing and release liner.
Discussion—Use of the word “tape” in this guide refers to PSA tapes and their components.
a combination of a pressure sensitive adhesive with a continuous flexible backing (cloth, paper, metal, or plastic) or with a backing and release liner.
Discussion—Use of the word "tape" in this guide refers to PSA tapes and their components.
A screening test that indicates the possible presence of a material of interest. A positive presumptive test result does not constitute the identification of that material. A negative presumptive test indicates that the material of interest was not detected; it is not confirmation of its absence. Presumptive tests are sensitive but not specific and can lead to false positive results.
A screening test which may be positive in the presence of a biological material of interest. Some presumptive tests are sensitive but not specific. A positive result indicates that further testing could be informative.
Action to eliminate the cause of a potential non-conformity or other potential undesirable situation. NOTE A preventive action is taken to prevent occurrence whereas a corrective action is taken to prevent recurrence.
The innate impulse of a canine to grasp prey. This drive can be delineated as 'instinctive' prey drive (prey consists of natural targets like birds, rodents, etc.) and 'imprinted' prey drive (prey consists of learned targets such as toys, balls, sticks, etc.). A canine's overall prey drive is a ratio of instinctive and imprinted prey drives.
small commercially-made spherical particles of a material. Discussion—Ammonium nitrate is commonly manufactured in prill form.
An enclosure used for long-term housing of the adult canine or puppy.
a high explosive that is extremely sensitive to initiation with a spark, weak flame, static electricity, or a mild shock, which is used to initiate secondary explosives.
the first instance in which an image is recorded onto any media that is a separate, identifiable object.
Discussion—Examples include a digital image recorded on a flash card or a digital image downloaded from the internet.
An impression on a document(s) or other substrate(s) beneath the originating document caused by the act of writing or other dynamic actions.
The delivery of a naturally occurring stimulus that requires no previous experience or learning to be reinforcing. It satisfies some biological need (i.e., food, water, air, social interaction).
a coating of adhesive-like material found between the tape adhesive and backing that serves as a bonding agent.
A cartridge case containing only a primer, without propellant or projectile.
A short polynucleotide chain, usually 18-30 bases long, which targets a specific region of the template DNA and allows a DNA polymerase to initiate synthesis of a complementary strand; two primers are required for amplification of a particular section of DNA. The primers are complementary to opposite strands and are designed to bracket the region of interest for amplification. Polymerization is initiated at the 3' end of the primer and extends in a 5 to 3 manner.
A short polynucleotide chain, usually 1830 bases long, which targets a specific region of the template DNA and allows a DNA polymerase to initiate synthesis of a complementary strand; two primers are required for amplification of a particular section of double-stranded DNA. The primers are complementary to opposite strands and are designed to bracket the region of interest for amplification. Polymerization is initiated at the 3' end of the primer and extends in a 5 to 3 manner.
ignition component of a cartridge.
Discussion—Commonly, a mixture of initiator, sensitizer, oxidant, fuel, and frictionator.
A short polynucleotide chain, usually 18 - 30 bases long, which targets a specific region of the template DNA and allows a DNA polymerase to initiate synthesis of a complementary strand; two primers are required for amplification of a particular section of double-stranded DNA. The primers are complementary to opposite strands and are designed to bracket the region of interest for amplification. Polymerization is initiated at the 3’ end of the primer and extends in a 5´ to 3´ manner.
a metal or plastic cap that contains a small amount of initiating explosive, which is readily ignited by shock.
Discussion—Primer caps (also referred to as simply ‘primers’) serve as the igniting element in small arms cartridges.
that portion of GSR resulting from the explosion of the primer compounds.
Short polynucleotide sequences which target a specific region of template DNA and allow a DNA polymerase to initiate synthesis of a complementary strand.
Print data includes writings, drawings, graphs, charts, photographs, images, and other material in paper or print form, including ESI that has been reproduced on paper or print media.
Portions of impression designating certain non-numeric designations located to the right of the first numeric segment.
Data collected when the subject was in a different, previous state/condition than thecurrent state of the subject. Examples are antemortem data, when postmortem dataexists or facial images of a missing person that are compared to those of the personbeing interviewed.
the direction of vibration to which light emerging from a polarizer has been restricted.
Discussion—In modern microscopes, the polarizer’s privileged direction is oriented in the east-west direction and the analyzer’s privileged direction is oriented in the north-south direction.
The use of biological modeling (i.e., statistical modeling informed by biological data), statistical theory, computer algorithms, and/or probability distributions to infer genotypes and/or calculate likelihood ratios
Software, or software and hardware, which utilizes a probabilistic genotyping approach to infer genotypes and/or calculate likelihood ratios
A quantified measure between zero and one indicating how probable or likely it is that an event will or has occurred. In the frequentist interpretation, probability is based on the rates at which events occur. In the Bayesian interpretation, probability reflects a degree of belief. On this scale, zero indicates impossibility and one indicates absolute certainty.
Probable cause exists when the facts and circumstances known to the officer would warrant a prudent person to believe a crime had been committed and the accused had committed it or that the evidence will be found in the place to be searched.
Possessing the potential to provide information that may be valuable to an investigation.
in facial identification, a facial image or template searched against the gallery in a facial recognition (FR) system.
Specified way to carry out an activity or a process. 1) Procedures can be documented or not. 2) When a procedure is documented, the term written procedure or documented procedure is frequently used. The document that contains a procedure can be called a procedure document.
specified way to carry out an activity or a process.
Discussion—(1) Procedures can be documented or not. (2) When a procedure is documented, the term “written procedure” or “documented procedure” is frequently used. The document that contains a procedure can be called a “procedure document.”
An established practice to be followed in performing a specified task.
set of interrelated or interacting activities which transforms inputs into outputsNOTE Adapted from ISO 9000:2005, definition 3.4.1.
Set of interrelated or interacting activities which transforms inputs into outputs
an analytical control that is derived from the labware, reagents, and solvents used in various stages of this procedure to check for interfering or contamination products introduced by labware or solvents.
A control to test a analytical process such as hydrolysis or oxidation of an analyte
Ordinate values that have been processed (e.g., trimmed, filtered, and/or interpolation applied).
in image and video analysis, any image that has undergone enhancement, restoration, or other operation.
result of a processNOTE 1 Four generic product categories are noted in ISO 9000:2005:- services (e.g. transport) (see definition in 3.4);- software (e.g. computer program, dictionary); - hardware (e.g. engine, mechanical part);- processed materials (e.g. lubricant).Many products comprise elements belonging to different generic product categories. Whether the product is then calledservice, software, hardware or processed material depends on the dominant element.NOTE 2 Products include results of natural processes, such as growth of plants and formation of other naturalresources.NOTE 3 Adapted from ISO/IEC 17000:2004, definition 3.3.
Results of a process
in forensic audio and video analysis, a device or software or both used to mix video or audio signals or both from two or more sources. (Compare routing switcher.)