coordinated universal time

noun coordinated universal time

• greenwich mean time — the time as measured on the prime meridian running through Greenwich, England: used in England and as a standard of calculation elsewhere.
• international atomic time — a system of measuring time based on atomic clocks that measure the second as the basic unit of time in the International System of Units (SI). Abbreviation: IAT.
• utc — (time, standard)   (UTC, World Time) The standard time common to every place in the world. UTC is derived from International Atomic Time (TAI) by the addition of a whole number of "leap seconds" to synchronise it with Universal Time 1 (UT1), thus allowing for the eccentricity of the Earth's orbit, the rotational axis tilt (23.5 degrees), but still showing the Earth's irregular rotation, on which UT1 is based. Coordinated Universal Time is expressed using a 24-hour clock and uses the Gregorian calendar. It is used in aeroplane and ship navigation, where it also sometimes known by the military name, "Zulu time". "Zulu" in the phonetic alphabet stands for "Z" which stands for longitude zero. UTC was defined by the International Radio Consultative Committee (CCIR), a predecessor of the ITU-T. CCIR Recommendation 460-4, or ITU-T Recommendation X.680 (7/94), contains the full definition. The language-independent international abbreviation, UTC, is neither English nor French. It means both "Coordinated Universal Time" and "Temps Universel Coordonné".
• universal time coordinated — incorrect term for coordinated universal time.