Calibration and Metrology Glossary of Terms
Accuracy:  Conformity to fact, exactness.
Calibration: To check, adjust, or determine by comparison with a standard, the readings from a measurement device.
International System of Units, SI: This is a coherent system of units defined through international consensus.   See also Guide to Fundamental SI Units 
Measurement: The act of measuring or the process of being measured
Metrology: The science of weights and measures. A system of weights and measures.
Precision:

The state or quality of being precise; exactness.

Primary Laboratories: These are metrology laboratories, like National Test Equipment, capable of realizing and maintaining an SI unit through a primary standard, and of carrying out calibrations with respect to the primary standard.
Primary Standard: This is a standard that is designated or widely acknowledged as having the highest metrological qualities in a specified field.
Resolution: The fineness of detail that can be distinguished (as in a moving coil meter face, for example).
Tolerance: The allowable variation from a standard.
Traceability: To have origins; be traceable - the 'pedigree' of a calibration.
Uncertainty:
 		 The estimated amount by which an observed or calculated value may differ from the true value.