Posted in Engineering, Organizations, Science 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)