Several languages have the adjectives in different order than English. UTC became the official abbreviation in 1967. Probably French.................
UTC is a “flavor” of UT (Universal Time) and has nothing to do with noun-adjective order. UT is determined by the orientation of the earth to the Celestial Sphere. There is a CONVENTIONAL relationship between “sidereal time” - time determined by the transit of celestial objects and UT. The convention is intended to keep UT close to mean solar time, but the relationship is not exact, but close enough for practical purposes.
UT0 - is “station time”, time measured by any station observing the celestial sphere, uncorrected for polar drift (Chandler Wobble).
UT1 - is derived by combining measurements by many stations, and accounts for polar drift
UT2 - is similar to UT1 but accounts for the seasonal variation in the length of day caused by snow and ice accumulation in the northern hemisphere. UT2 is more uniform than UT1, as measured by atomic clocks. Considered obsolete these days because of the widespread availability of atomic time.
UTC - is an atomic timescale kept within 0.9 seconds of UT1 by the addition and subtraction of leap seconds. UTC is always offset from TAI by an integer number of leap seconds.
Other interesting and important timescales are
TAI - International Atomic Time, time kept by combining time determined by atomic clocks in dozen of national laboratories. TAI is “proper time on the geoid”, the conventional co-rotating mean sea level surface of the earth. Sea level varies due to local gravitational anomalies.
TT - Terrestrial Time, an atomic timescale intended to be a continuation of an older astronomical timescale called Ephemeris Time. TT is exactly 32.184 seconds ahead of TAI.
GPS - GPS time is time in seconds since January 6, 1980, the GPS epoch. GPS time is always exactly 19 seconds behind TAI.
GMT - Greenwich Mean Time is variously defined and deprecated in technical work. In practice it is a synonym for UTC
ZULU - ZULU was and is the the NATO designation for the time zone centered on the prime meridian. In practice ZULU time is identical to UTC. Colloquially, GMT, ZULU, and UTC are used interchangeably.