- C2 stands for Command & Control
- C3 stands for Axis (second cervical vertebra; common name)
- C4 stands for Ethane
- C5 stands for Canoe (two person)
- C6 stands for Capability 2
- C7 stands for Clarity 2 (Everquest)
- C8 stands for Coke 2
- C9 stands for Croc 2 (game)
- C10 stands for Schedule II Controlled Substance (USA)
- C11 stands for Costlink Controller
- C12 stands for CPU State 2 (partial-sleep power-down mode, computing)
C2