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.
Administrative Review
OSAC Preferred
Evaluation of records (3.49) to verify consistency with the forensic service provider’s (3.26) administrative policies and with editorial correctness
Numbers in the parenthesis refers to additional terms in the standard.
Also referenced in ANSI/ASB 143 Standard for Technical Review in Friction Ridge Examination.
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.
Authentication, Biometric
OSAC Preferred
Process of assessing a level of confidence in identify or identification.
Bias, Cognitive
OSAC Preferred
A tendency for an individual’s preexisting beliefs, expectations, motives, or the situational context to influence their sampling, observations, results, interpretations, or opinions, or their confidence in the aforementioned.
Also referenced in ANSI/ASB Standard 024 Standard for Training and Certification of Canine Detection of Humans: Location Check Using Pre‐scented Canines, ASB Technical Report 025 Crime Scene/Death Investigation – Dogs and Sensors – Terms and Definitions, ANSI/ASB Standard 024 Standard for Training and Certification of Canine Detection of Humans: Location Check Using Pre‐scented Canines, ANSI/ASB Standard 088 General Guidelines for Training, Certification, and Documentation of Canine Detection Disciplines, ANSI/ASB Standard 154 Standard for Training on Testimony for Forensic Biology
Bias, Confirmation
OSAC Preferred
A tendency to search for, collect, perceive, or interpret information in a manner that supports preconceptions, expectations, or desires.
NOTE: This is a type of cognitive bias.
Bias, Contextual
OSAC Preferred
A tendency for exposure to or knowledge of case-specific information to affect the impartial collection, perception, or interpretation of evidence.
NOTE: This is a type of cognitive bias.
Also referenced in ASB Technical Report 025, Crime Scene/Death Investigation – Dogs and Sensors – Terms and Definitions
Bias, Statistical
OSAC Preferred
A systematic tendency for estimates or measurements to be above or below their true values.
NOTE 1: Statistical bias arises from systematic as opposed to random error.
NOTE 2: Statistical bias can occur in the absence of prejudice, partiality, or discriminatory intent.
Chain Of Custody
OSAC Preferred
chronological record (3.49) of the transfer, handling and storage of an item (3.33) from its point of collection to its final return or disposal
Numbers in the parenthesis refers to additional terms in the standard.
Also referenced in ANSI/ASB 019, Wildlife Forensics General Standards and ANSI/ASB Technical Report 025, Crime Scene/Death Investigation - Dogs and Sensors - Terms and Definitions, ANSI/ASB Standard 170, Standard for Veterinary Forensic Postmortem Examination, ANSI/ASB Standard 169 Standard for Clinical Veterinary Forensic Examination.
ANSI/ASTM E1732 Standard Terminology Relating to Forensic Science.
Characteristics, Individual
OSAC Preferred
An attribute or combination of attributes that are variably acquired with the potential to differentiate a single member of a particular class, category, or group.
Also referenced in ANSI/ASTM E1732 Standard Terminology Relating to Forensic Science.
Characteristics(s), Class
OSAC Preferred
An attribute or combination of attributes with the potential to establish membership in, but are unable to differentiate a single member of, a particular class, category, or group.
Also referenced in ANSI/ASTM E1732 Standard Terminology Relating to Forensic Science.
Competency Testing
OSAC Preferred
Evaluation of a persons knowledge and ability to perform work before authorization to do so independently.
Also referenced in ANSI/ASB Standard 099 Standard for Footwear/Tire Examination Proficiency Testing Program.
Control
OSAC Preferred
Material of established origin used to evaluate the performance of a test or comparison. Or A test performed to demonstrate that a test method works correctly and to ensure that data are valid. Positive controls confirm that the procedure will produce the expected result. Negative controls confirm that the procedure does not produce an unintended result.
Also referenced in ANSI/ASB 017 Standard Practices for Measurement Traceability in Forensic Toxicology,
ANSI/Academy Standards Board (ASB), Crime Scene/Death Investigation - Dogs and Sensors - Terms and Definitions, ANSI/ASB 056 Standard for Evaluation of Measurement Uncertainty in Forensic Toxicology ANSI/ASB 046 Wildlife Forensics Validation Standards—STR Analysis.
Exclusion
OSAC Preferred
A result that compared items did not originate from the same source, are not the same substance, or do not share the same composition or classification, based on an exclusionary difference.
Also referenced in ASB 097, Terminology Used for Forensic Footwear and Tire Evidence.
Exclusionary Difference
OSAC Preferred
a difference in one or more characteristics between compared items that is sufficient to determine that the compared items did not originate from the same source, are not the same source, or do not share the same composition or classification.
Also referenced in ANSI/ASTM E1732 Standard Terminology Relating to Forensic Science
ANSI/ASTM E1732 Discussion—What is sufficient depends on the performance and limitations of the method used on the material in question.
Forensic
OSAC Preferred
related to methods (3.35), techniques and processes used for recovery (3.51), analysis (3.2), interpretation (3.30) and reporting of observations (3.36) and opinions (3.37), which can be used for law enforcement investigations or for legal proceedings
Numbers in the parenthesis refers to additional terms in the standard.
Also referenced in ANSI/ASB Standard 169 Standard for Clinical Veterinary Forensic Examination, ANSI/NIST-ITL 1-2011 Update:2015 Data Format for the Interchange of Fingerprint, Facial & Other Biometric Information. ANSI/National Institute of Standards and Technology, 2011
Forensic Science
OSAC Preferred
The application of scientific principles and techniques to matters of criminal justice especially as relating to the collection, examination, and analysis of physical evidence.
Forensic Science Service Provider (FSSP)
OSAC Preferred
An organization or individual that provides forensic science services.
Also referenced in ANSI/ASB 017 Standard Practices for Measurement Traceability in Forensic Toxicology, ASTM E1732 Standard Terminology Relating to Forensic Science, ANSI/ASTM E2917-24a Standard Practice for Forensic Science Practitioner Training, Continuing Education, and Professional Development Programs, ANSI/ASTM E3255-21 Standard Practice for Quality Assurance of Forensic Science Service Providers Performing Forensic Chemical Analysis, ANSI/ASB 142-22 Best Practice Recommendations for the Resolution of Conflicts in Friction Ridge Examination, ANSI/ASB Standard 157-23 Required Components for a Proficiency Testing Program in Bloodstain Pattern Analysis
Forensic Service Provider (FSP)
OSAC Preferred
organization that performs all or part of the forensic process (3.25).
Note 1 to entry: A forensic service provide can be a large or small organization, including an organization consisting of a single examiner (3.20)
Numbers in the parenthesis refers to additional terms in the standard.
Also referenced in ANSI/ASB 145 Standard for Consultation During Friction Ridge Examination, ANSI/ASB Best Practice Recommendation 144 Best Practice Recommendations for the Verification Component in Friction Ridge Examination, ANSI/ASB Best Practice Recommendation 165 Best Practice Recommendation for Analysis of Friction Ridge Impressions, ANSI/ASB Best Practice Recommendation 166 Best Practice Recommendation for Comparison and Evaluation of Friction Ridge Impressions, ANSI/ASB 014 Standard for Friction Ridge Examination Training Program, ANSI/ASB Standard 015 Standard for Examining Friction Ridge Impressions, ANSI/ASB 168 Standard for Testimony Monitoring in Friction Ridge Examination, ANSI/ASB 143 Standard for Technical Review in Friction Ridge Examination, ANSI/ASB 167 Standard for Reporting Results from Friction Ridge Examinations.
Forensic Services
OSAC Preferred
Activities included in the collection, examination, and analysis of items and reporting of observations and opinions for matters of criminal justice, or for regulatory, or legal proceedings.
Identification
OSAC Preferred
Assignment or distinguishment of an unknown object, compound, biological sample, or other evidence to the most specific class or level reliably attainable under the analytical scheme used.
NOTE: Uncertainty and limitations always remain in any finding
NOTE: Presence of this term in the OSAC Lexicon does not endorse its use in place of relevant interpretation scale levels for the discipline or method
NOTE: Although this term is used informally, the term should not be used in written or oral interpretations or opinions for any discipline for conveying source of the evidence.
Also referenced in ASB TR 097, Terminology Used for Forensic Footwear and Tire Evidence, ANSI/ASTM E1732-24e1 Standard Terminology Relating to Forensic Science.
Interlaboratory Comparison
OSAC Preferred
evaluation of part or all of the forensic process (3.25) when applied to the same or similar items (3.33) and conducted under the same or similar conditions by two or more forensic service providers (3.26). Note 1 to entry: A proficiency test (3.42) is a type of interlaboratory comparison
Numbers in the parenthesis refers to additional terms in the standard.
Also referenced in ANSI/ASTM E3255-21 Standard Practice for Quality Assurance of Forensic Science Service Providers Performing Forensic Chemical Analysis, ANSI/ASB 153 Standard Practices for Proficiency Testing for Forensic Toxicology Laboratories and Breath Alcohol Programs, ANSI/ASTM E1732 Standard Terminology Relating to Forensic Science.
Interpretation
OSAC Preferred
Explanations for the observations, data, and calculations.
Also referenced in ANSI/ASB 040 Standard for Forensic DNA Interpretation and Comparison Protocols, ANSI/ASB 038 Standard for Internal Validation of Forensic DNA Analysis Methods, ANSI/ASB 015-24 Standard for Examining Friction Ridge Impressions, ANSI/ASB Best Practice Recommendation 166 Best Practice Recommendation for Comparison and Evaluation of Friction Ridge Impressions, ANSI/ASB 175 Standard for Interpreting, Comparing and Reporting DNA Test Results Associated with Failed Controls and Contamination Events, ANSI/ASB 123 Standard for Routine Internal Evaluation of a Laboratory’s DNA Interpretation and Comparison Protocol, ANSI/ASB Best Practice Recommendation 165 Best Practice Recommendation for Analysis of Friction Ridge Impressions, ANSI/ASB 167 Standard for Reporting Results from Friction Ridge Examinations
Intralaboratory Comparison
OSAC Preferred
evaluation of part or all of ther forensic process (3.25) when applied to the same or similar items (3.33) and conducted under the same or similar conditions by two or more examiners (3.20) within the same forensic service provider (3.26)
Numbers in the parenthesis refers to additional terms in the standard.
Also reference in ANSI/ASTM E3255-21 Standard Practice for Quality Assurance of Forensic Science Service Providers Performing Forensic Chemical Analysis, ANSI/ASTM E1732 Standard Terminology Relating to Forensic Science, ANSI/ASB 153 Standard Practices for Proficiency Testing for Forensic Toxicology Laboratories and Breath Alcohol Programs.
Observation
OSAC Preferred
DEPRECATED: finding
result of analysis (3.2) of items (3.33) or of the scene (3.58)
Note 1 to entry: An observation can be the result of human perception-based analysis, instrumental analysis, or a combination of the two.
Numbers in the parenthesis refers to additional terms in the standard.
Opinion
OSAC Preferred
View, judgment, belief - takes into consideration other information in addition to observations, data, calculations, and interpretations.
Also referenced in ANSI/ASB 167 Standard for Reporting Results from Friction Ridge Examinations.
Peer Review
OSAC Preferred
An independent evaluation of a scientific, professional, or academic manuscript or publication by one or more qualified parties to evaluate the claims, methods, interpretations, and conclusions.
Also referenced in ANSI/ASB Technical Report 025, Crime Scene/Death Investigation - Dogs and Sensors - Terms and Definitions, ASTM E2916-13 Standard Terminology for Digital and Multimedia Evidence Examination.
Performance Monitoring
OSAC Preferred
The ongoing process of evaluating a forensic service providers ability to perform work. Examples include observation-based evaluations, intralaboratory comparisons, interlaboratory comparisons, and proficiency testing.
Proficiency Testing
OSAC Preferred
evaluation of participant performance using pre-established criteria by means of interlaboratory or intralaboratory comparisons.
Also referenced in ASTM E1732-24ae1 Standard Terminology Relating to Forensic Science, ANSI/ASTM E1301-95 Standard Guide for Proficiency Testing by Interlaboratory Comparisons, ANSI/ASB Standard 153 Standard Practices for Proficiency Testing for Forensic Toxicology Laboratories and Breath Alcohol Programs.
Reliability, Evidentiary/Legal
OSAC Preferred
Credibility and trustworthiness of proffered evidence.
Reliability, Statistical
OSAC Preferred
Consistency of results as demonstrated by reproducibility or repeatability.
Repeatability
OSAC Preferred
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.
Replicability
OSAC Preferred
See "Reproducibility"
Reproducibility
OSAC Preferred
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.
Result
OSAC Preferred
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
Technical Review
OSAC Preferred
DEPRECATED: peer review
evaluation of all supporting records (3.49) from the examination (3.18) and the report (3.55), if prepared, to evaluate observations (3.36) and assess whether there is an appropriate and sufficient basis for any opinions (3.37). Note 1 to entry: Technical review can also be applicable to observations and opinions that are communicated other than by way of report (see ISO 21043-5).
Numbers in the parenthesis refers to additional terms in the standard.
Also referenced in ANSI/ASB 019 Wildlife Forensics General Standards, ANSI/ASB Technical Report 025, Crime Scene/Death Investigation - Dogs and Sensors - Terms and Definitions, ANSI/ASB 063 Implementation of 3D Technologies in Forensic Firearm and Toolmark Comparison Laboratories, ANSI/ASB 142-22 Best Practice Recommendations for the Resolution of Conflicts in Friction Ridge Examination, ANSI/ASTM E3392-24 Standard Guide for Forensic Physical Fit Examination, ANSI/ASTM E1732 Standard Terminology Relating to Forensic Science, ANSI/ASB Standard 099 Standard for Footwear/Tire Examination Proficiency Testing Program, ANSI/ASB 168 Standard for Testimony Monitoring in Friction Ridge Examination, ANSI/ASB 143 Standard for Technical Review in Friction Ridge Examination
Validation
OSAC Preferred
A process of evaluating a system, method, or component, to determine that requirements for an intended use or application have been fulfilled.
Also referenced in ANSI/ASB Technical Report 025, Crime Scene/Death Investigation - Dogs and Sensors - Terms and Definitions, ANSI/ASB 018 Standard for Validation of Probabilstic Genotyping Systems, ANSI/ASB 020 Standard for Validation Studies of DNA Mixtures, and Development and Verification of a Laboratory's Mixture Interpretation Protocol, ANSI/ASB 038 Standard for Internal Validation of Forensic DNA Analysis Methods, ANSI/ASB 019 Wildlife Forensics General Standards, ANSI/ASB 047 Wildlife Forensics Validation Standard and Validating New Primers for Sequencing, ANSI/ASB 022 Standard for Forensic DNA Analysis Training Programs, ANSI/ASB 063 Implementation of 3D Technologies in Forensic Firearm and Toolmark Comparison Laboratories, ASTM E1732 Standard Terminology Relating to Forensic Science, ANSI/ASB Standard 072 Standard for the Validation of Procedures in Bloodstain Pattern Analysis, ANSI/ASB 046 Wildlife Forensics Validation Standards—STR Analysis.
Also referenced in ISO/IEC 17025:2017 General Requirements For The Competence Of Testing And Calibration Laboratories. International Organization for Standardization/International Electrotechnical Commission, Chemin de Blandonnet 8, CP 401, 1214 Vernier, Geneva, Switzerland, 2017.
Verification, Analytical
OSAC Preferred
Performing subsequent testing to ascertain if the results are concordant.