Universal Time as periodically adjusted to coordinate with atomic clocks: it serves as the official international basis for standard time: abbrev. UTC
See Coordinated Universal Time in American Heritage Dictionary 4
(kō-ôrˈdn-āˌtĭd)
noun Abbr. UTC
Universal time, taking into account the addition or omission of leap seconds by atomic clocks each year to compensate for changes in the rotation of the earth.