This abbreviation is international: Koordinierte Weltzeit (UTC)
Before the abbreviation was standardised, the abbreviation Coordinated Universal Time in the English language was CUT, whereas the French version Temps Universel Coordonné was TUC. However, the International Telecommunication Union and the International Astronomical Union were keen to establish a common abbreviation for all languages. In order not to prefer either of the two languages, the compromise UTC was chosen as the internationally uniform abbreviation, which is also arranged alphabetically in the other derivatives of Universal Time (such as UT1, UT2). Based on this definition, the C stands for coordinated (French coordonné) leap seconds.
The official abbreviation for Coordinated Universal Time is UTC. This abbreviation arose from a desire by the International Telecommunication Union and the International Astronomical Union to use the same abbreviation in all languages. English speakers originally proposed CUT (for "coordinated universal time"), while French speakers proposed TUC (for "temps universel coordonné"). The compromise that emerged was UTC, which conforms to the pattern for the abbreviations of the variants of Universal Time (UT0, UT1, UT2, UT1R, etc.).
Still, familiarity cannot be guaranteed if you care for German speakers. Those often have trouble to even recognise MEZ (CET). To aid understanding at the cost of precision and international agreements, you might just use Weltzeit (~GMT).