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.
alpha
symbol representing the lowest of the three prin- cipal refractive indices of a biaxial crystal.
Alteration
The result of changing something.
alteration
A modification made to a document by any combination of physical, chemical, or mechanical means including, but not limited to, obliterations, additions, over writings, or erasures. (ANSI/ASB Standard 035)
alteration
A modification made to a document by any combination of physical, chemical, or mechanical means including, but not limited to, obliterations, additions, overwritings, or erasures. (ANSI/ASB Std 035)
Altered Stain
alternate light source
Equipment used to produce light at various wavelengths to enhance or visualize potential items of evidence.
alternate light source (ALS)
Equipment used to produce light at various wavelengths to enhance or visualize potential items of evidence.
NOTE A monochromatic light source can be used in examination of an animal’s body to enhance visualization, identification, documentation, and collection of bodily fluids and fibers as potential evidence.
Alternate Light Source (ALS)
Equipment used to produce light at various wavelengths to enhance or visualize potential items of evidence.
Ambient
Someone's or something's surroundings, especially as they pertain to the local environment; for example, ambient air and ambient temperature.
amended report
A report used to document any modifications from a previously issued report, particularly those that affect or correct an original result or interpretation.
ammunition
Unfired cartridge(s) designed to be discharged in a firearm.
Ampacity
The maximum current, in amperes, that a conductor can carry continuously under the conditions of use without exceeding its temperature rating.
Ampere
The unit of electric current that is equivalent to a flow of one coulomb per second; one coulomb is defined as 6.24 _ 1018 electrons.
Amplicon
Any PCR amplification product.
amplification
An increase in the number of copies of a specific DNA fragment; can be in vivo or in vitro. In forensic DNA testing laboratories, this refers to the use of the PCR technique to produce many more copies of DNA at specific genetic loci.
amplification
The process by which the number of copies of a specific DNA fragment is increased.
Amplification
An increase in the number of copies of a specific DNA fragment. In forensic DNA testing laboratories, this refers to the use of the PCR technique to produce many more copies of fragments at specific genetic loci from samples of known and unknown origin for the purpose of generating DNA profiles for comparison.
Amplification
An increase in the number of copies of a specific DNA fragment; can be in vivo or in vitro. In forensic DNA testing laboratories, this refers to the use of the PCR technique to produce many more copies of DNA at specific genetic loci.
Anagen
Analysis
OSAC Preferred
part of the examination (3.18) consisting of detecting, measuring or comparing the properties of items (3.33), in order to obtain observations (3.36)
Note 1 to entry: Analysis can be either instrumental, human perception-based, or a combination of the two.
Numbers in the parenthesis refers to additional terms in the standard.
analysis
The “unknown” item is classified according to its properties or characteristics. These properties can be directly observable, measurable, or inferred. (based on Huber, 1959)
analysis (phase of the examination process)
The interpretation of observed data in a friction ridge impression in order to categorize its suitability/utility.
analysis (phase of the examination process)
The interpretation of observed data in a friction ridge impression in order to categorize its utility.
analysis (phase of the examination process)
The interpretation of observed data in a friction ridge impression in order to categorize its utility.
analysis (phase of the examination process)
The interpretation of observed data in a friction ridge impression in order to categorize its suitability/utility.
Analysis, Comparison, Evaluation (see individual terms) (ACE)
A summary by Huber (1959) of three distinct stages through which the forensic or other examiner must pass, consciously or otherwise, in the course of any comparative examination. NOTE These terms are similar to “study, comparison and interpretation” and “recognition, comparison, and correct interpretation. (Osborn, AS, 1910, pp 89, 105)
Analyst
A qualified individual who conducts and/or directs the analysis of forensic casework samples, interprets data, reaches conclusions, and/or issues reports concerning conclusions.
Analyst
A qualified individual who conducts and/or directs the analysis of forensic casework samples, interprets data, reaches conclusions, and/or issues reports concerning conclusions.
Analyte
A chemical substance to be identified and/or measured.
analyte
chemical substance to be identified and/or measured
analytes of interest
drugs, drug metabolites, and other chemicals included within the analytical scope of a test method
analytical peak
most intense X-ray peak of a given element.
analytical run “batch”
Set of standards, controls, and/or case samples that are contemporaneously prepared and/or analyzed in a particular sequence
analytical run “batch”
set of case samples, controls, and/or calibrators that are contemporaneously prepared and/or analyzed in a particular sequence
Analytical Scope
A selection of drugs, drug metabolites and other chemicals covered in an analytical testing scheme.
Analytical Scope
A selection of drugs, drug metabolites, and other chemicals covered in an analytical testing scheme.
Analytical Scope
A selection of drugs, drug metabolites, and other chemicals covered in an analytical testing scheme.
analytical scope
selection of drugs, drug metabolites, and other chemicals covered in an analytical strategy
Analytical Sensitivity
The lowest amount of an analyte that can be reliably measured in a specimen by a laboratory test; may be a decision point, a limit of detection or a limit of quantitation
Analytical Sensitivity
The lowest amount of an analyte that can be reliably measured in a specimen by a laboratory test;may be a decision point, a limit of detection, or a lower limit of quantitation.
analytical sensitivity
lowest amount of an analyte that can be reliably measured in a specimen by a laboratory test; may be a decision point, a limit of detection, or a lower limit of quantitation
analytical strategy
choice of method(s) (3.35) and the sequence of analysis
Note 1 to entry: An analytical strategy is based in part on relevant case questions and background information.
analytical strategy
choice of methods and the sequence of analysis
analytical threshold
The minimum peak height (Relative Fluorescence Units, in RFUs) requirement at and above which detected peaks on a DNA electropherogram can be reliably distinguished from instrument background noise.
Analytical Threshold
1) The minimum height requirement at and above which detected peaks on a STR DNA profile electropherogram can be reliably distinguished from background noise; peaks above this threshold are generally not considered noise and are either artifacts or true alleles. 2) A 'Relative Fluorescence Units' (RFU) level determined to be appropriate for use in the PCR/STR DNA typing process; a minimum threshold for data comparison is identified by the specific forensic laboratory through independent validation studies.
analytical threshold
The minimum height requirement at and above which detected peaks on an STR DNA profile electropherogram can be reliably distinguished from instrument background noise; peaks above this threshold are generally not considered noise and are either artifacts or true alleles.
anatomical method
A method of estimating living stature that involves measuring all bones contributing to stature, summing those measurements, and correcting for the missing soft tissue.