| Abbreviation | Definition |
|---|---|
| CCT | Cocos Islands Time |
| CDT | Central Daylight Time |
| CDT | Central Daylight Time [UTC - 0500] |
| CDT | Cuba Daylight Time |
| CEDT | Central European Daylight Time |
| CEST | Central Europe Summer Time |
| CEST | Central European Standard Time |
| CET | Central European Time |
| CHADT | Chatham Island Daylight Time [UTC +1345] |
| CHAST | Chatham Island Standard Time [UTC +1245] |
| CHST | Chamorro Standard Time |
| CIDT | Chatham Islands Daylight Time [UTC + 1345] |
| CIST | Chatham Islands Standard Time [UTC + 1245] |
| CKT | Cook Island Time |
| CLST | Chile Summer Time |
| CLT | Cairo Local Time |
| CLT | Chile Standard Time |
| CM | Central Meridian |
| CMP | Central, Mountain, Pacific |
| CMT | Cyberterra Mean Time |