The list of terms below is a glossary for the users of standard-frequency and time-signal services. It is taken from Recommendation ITU-R TF.686, the International Vocabulary of basic and general terms in Metrology (VIM), published by ISO, and other terms in general usage in the field of frequency and time. Precise time measurements may often be affected by relativity effects. The terms and definitions below do not in all cases imply incorporation of, or indicate the need for, the consideration of these effects. Two types of terms are presented; those typically used within the standard-frequency and time-signal services and those of more general use, but specifically relevant to this field. For the latter, an attempt has been made to provide substantial agreement with the definitions contained in the International Electrotechnical Vocabulary (IEV). The equivalence of the terms are given in French and Spanish (terms printed in italics). Terms taken from Recommendation ITU-R TF.686 are not marked, terms from the ITU Radio Regulations and the ISO publications are indicated as “RR” and “ISO”, respectively. Additional terms may be found in the National Institute of Standards and Technology Technical Note 1297, 1994, “Guidelines for Evaluating and Expressing the Uncertainty of NIST Measurement Results.”