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.
Polynuclear Aromatic Hydrocarbon (PNA)
Polyurethane (Pu)
Polyvinyl Chloride (Pvc)
Polyvinylsiloxane
Popstats
A program in the CODIS software suite used to provide statistical estimates.
Population
A group of organisms of the same species in a defined geographic area, such that any pair of members can interbreed.
population
A group of organisms of the same species in a defined geographic area, such that any pair of members can interbreed.
population
A group of organisms of the same species in a defined geographic area such that any pair of members can interbreed.
Population
Population
population
Individuals grouped by shared factors such as geography, biology, culture, language, etc.
population
A group of organisms of the same species in a defined geographic area, such that any pair of members can interbreed.
population affinity
A measure (e.g., distance, probability of membership) of similarity between the individual and reference groups.
population genetics
The study of genes and allele frequencies in populations.
Population Studies
population substructure
The existence of subpopulations with different allele frequencies.
portrait mode
A vertical orientation of a document or image.
Pose
Position And Orientation Of Wear
Positional Tooth Numbering
Assignment of tooth numbers based upon the location of the teeth. This is in contrast tomorphological tooth numbering, which assigns a tooth number based upon position,the shape of the tooth. For most cases, the tooth number assignment would be the same.Differences arise only in unusual cases.
Positive Alert
A trained detection alert in the presence of the target odor/scent.
Positive Control
An analytical control sample that is used to determine if a test performed properly; this control consists of the test reagents and a known sample that will provide an expected positive response with the test. NOTE For DNA testing, positive controls include positive amplification controls and may include extraction positive controls.
positive control
An analytical control sample that is used to determine if a test performed properly. This control consists of the test reagents and a known sample that will provide a positive response in the test.
positive control
An analytical control sample that is used to determine if a test performed properly. This control consists of the test reagents and a known sample that will provide a positive response in the test.
Positive Control
positive control
An analytical control sample that is used to determine if a test performed properly; this control consists of the test reagents and a known sample that will provide an expected positive response with the test.
NOTE For DNA testing, positive controls include positive amplification controls and may include extraction positive controls.
Positive Impression
Positive Integer
An integer greater or equal to 1. The value 0 is not included in this use of the term.
Positive Location Check
A type of search conducted in a specific area in which an existing human scent in the environment matches that of the scent article presented to the canine.
Positive Predictive Value
Within this document the positive predictive value is defined as the fraction of identifications that correspond to true known matches, TP/(TP+FP) where TP (True Positives) is the number of correctly identified Known Matches and FP (False Positives) is the number of Known Non-Matches incorrectly determined to be an Identification.
Positive Reinforcement
A reward given after a response or as the response occurs that increases the probability of that response recurring. For example, if a canine is rewarded for sitting by being given a treat the canine is more likely to sit again.
Positive Testing
Checking to confirm that the natural (or usual) inputs yield the expected output.
Possession
Upon presentation of the reward article, the canine takes the article without hesitation, and maintains a firm grip.
Post-Amplification Quantification
An analytical procedure to determine the amount of amplicon obtained after DNA amplification.
Postmortem
After death.
postmortem damage
A skeletal defect that occurred after a bone has lost its biomechanically fresh (visco-elastic) properties.
postmortem examination
Examination of a decedent and associated information by a forensic pathologist or other medical personnel certified to perform such examinations; this may include autopsy, external examination, ancillary tests, evaluation of circumstances, review of medical records and other contextual information.
postmortem interval (PMI)
The time between death and discovery of the decedent or remains; also known as time since death.
postmortem interval (PMI)
The time between death and discovery of the decedent’s remains; also known as time since death.
Postmortem Root Banding
postmortem toxicology
analysis of specimens from decedents in medicolegal death investigations to determine the presence (or absence) of chemical substances and their role, if any, in the cause of death
Posture
The position in which the body is held.
Pound-force/lbf
One pound-force, 1 lbf, is defined as the weight of a one avoirdupois pound, 1 lb, mass at standard gravity.1 lbf (pound-force) 4.448 N (newtons)1 N (newton) 0.2248 lbf (pound-force)NOTE The SI unit of force is the newton, symbol N. In the U.S., it is customary to specify the trigger pull force in pound-force, symbol lbf.NOTE Pound-force lbf is sometimes referred to as pound lb where the context refers to force rather than mass.
Pour Pattern
A disparaged term for an irregular pattern that may be observed at a fire scene. This kind of pattern should not be identified as resulting from ignitable liquids on the basis of observation of the visual appearance alone.
Power
A property of a process, such as fire, which describes the amount of energy that is emitted, transferred, or received per unit time and is measured in joules per second (J/s) or watts (W).
Ppi
Pixels per inch.
Ppmm
Pixels per millimeter.
Praise Off
Physically removing the canine, after he has shown a response, from the area or item without causing any physical discomfort to the canine, while verbally praising the canine.
Pre-Scenting
A sample target scent that is presented to the canine prior to deployment. The canine's objective is to match the scent article to the target scent. This is commonly used in tracking/trailing/location checks and/or scent discrimination line ups.
Pre-Scenting Canines
A type of canine that smells a sample target odor pad (scent article) prior to deployment. The canine's objective is to match the pre-scented pad to the target scent. This is commonly used in tracking/trailing and/or scent discrimination line ups.