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.
X-rays resulting from scattered Bremsstrahlung and coherently and incoherently scattered tube target peaks.
A recovered sample from a source believed not to have been exposed to pGSR.
A thin flexible material to which adhesive is applied.
In facial identification, a light source placed behind a subject in a controlled capture that reduces back-ground shadows.
A characteristic of a subject or an object that is illuminated from behind.
A technique that uses high energy electrons that originate from the primary electron beam of the SEM and are elastically reflected by the specimen to create an image of the sample. The probability of backscattering is proportional to atomic number.
A layer applied to the top side of the backing. Its purpose is to coat and fill a porous surfaced backing with a material that is inert to the adhesive formulation to be used.
A bloodstain pattern resulting from blood drops which can be produced when a projectile creates an entrance wound.
A canine that is trained, certified, and/or works with more than one certified canine handler.
one or more colored areas (circular to elongated shape) on a TLC plate produced by the separation of the dye components for a particular combination of solvent and stationary phase. Bands are created as the solvent (mobile phase) moves past and reacts with the solute, migrating from the origin.
Items used to conceal a target source in order to test the canine to perform the bark indication.
a filter used in fluorescence microscopy that absorbs excitation energy that has been reflected by the sample, selectively transmitting only wavelengths of light greater than the cut-off wavelength, or within a specific wavelength range
The main "high explosive" charge.
Most abundant ion in the mass spectrum. In plotting the mass spectrum, all other ions are normalized to the base peak
The normal frequency of occurrence of a specified response per unit of time for that individual canine or group of canines.
A set of standards, controls, and/or case samples that are contemporaneously prepared, extracted, and analyzed in a particular sequence
In facial identification, a mode of searching records in an automated system in which a group of probes are simultaneously or sequentially launched.
See batch mode search
The FBI's Biometric Center of Excellence.
Biometric Data Block used in CBEFF.
A rounded mass of resolidified metal on the end of the remains of an electrical conductor or conductors that was caused by arcing and is characterized by a sharp line of demarcation between the melted and unmelted conductor surfaces.
A hoop of steel wires within a tire that hold the tire on the rim.
the bright halo near the boundary of a fiber that moves with respect to that boundary as the microscope is focused through best focus when the fiber is mounted in a medium that differs from its refractive index.
a method for determining the refractive index of a fiber relative to its mountant by noting the direction in which the Becke line moves when the focus is changed.
Any measurable, physical response of a canine. Can be voluntary (goal directed) or involuntary (reflexive).
The application of a behavioral technique (e.g., positive reinforcement) to change a behavior.
A series of independent behaviors that are linked together.
A system of processes, checks and testing that may deliver an outcome that has fewer problems and fewer unforeseen complications, and that may combine the attributes of the most efficient and most effective ways of accomplishing a task based on proven and provable methods, while maintaining overall operational integrity and remaining within the bounds of legally accepted practices.
Preconception; prejudice; taint; partiality. Since most persons have biases, the issue is whether the bias is such that impartiality cannot be achieved and a fair outcome cannot occur. Any predisposition that a judge or arbitrator may have may be grounds for recusal. Any predisposition that a witness may have may be grounds for impeachment by cross-examination. Any predisposition that a juror may have may be grounds for excusal determined by through a process known as voir dire. This use of the term 'bias' is not that as used in statistical evaluations. (See cognitive bias, contextual bias, and experimental bias.)
The difference between the expectation of the test results and an accepted reference value.
An estimate of systematic measurement error, calculated as the difference between the mean of several measurements under identical conditions, to a known true value. It is often reported as a percent difference
The variance of measured results as influenced by human perceptions or systemic factors. Note: It is beyond the scope of this document to outline the numerous types of biases
A tire that has plies which cross over one another at an angle.
A bias tire with added reinforced belts that lie beneath the tread.
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.
An oriented polypropylene film in which the polymer has been stretched in both the machine direction and cross direction during the manufacturing process. Tapes with such films cannot be torn by hand.
Allele designations corresponding to the window of fragment sizes for each allele, determined by empirical testing
A high explosive consisting of a separate oxidizer and fuel that can be acquired, stored, or shipped individually, but when combined form an explosive mixture.
A nonvolatile portion of the liquid vehicle of a coating, which serves to bond or cement the pigment particles together.
A non-volatile portion of a paint which serves to bind or cement the pigment particles together.
In facial identification,(1) any technique used by a facial recognition (FR) system to organize or optimize searching based upon some piece(s) of metadata; (2) the process of parsing (examining) or classifying data to accel- erate or improve biometric matching
A commercial product comprised of collapsible foam developed for recording of three-dimensional anatomical impressions of the feet, but also used for the recording of footwear outsoles.
The age corresponding with the developmental, degenerative, biochemical or isotopic status of an individual. Note: The rate at which organ systems age may differ from the individual's chronologic age.
Any liquid biological specimen that is typically pipetted for analysis (e.g., blood, urine, bile, serum, vitreous humor, oral fluid)
The submission of a biometric reference as a probe against a biometric system for identification (one-to-many) or verification (one-to-one). (Compare at- tempt.)
the numerical difference in refractive indices (n) for a fiber, given by the equation: |n||n|
Property of some crystals, those having more than one refractive index; this will result in interference colors which are viewed through a polarized light microscope.
Property of some crystals, those having more than one refraction index; this property will result in interference colors, which are viewed through a polarized light microscope.
Property of some crystals, those having more than one refractive index; this property will result in interference colors, which are viewed through a polarized light microscope.