| Abbreviation | Definition |
|---|---|
| CFSU | Cosmic Functional Size Unit |
| CFT | Cubic Feet |
| CFU | Colony Forming Unit |
| CG | Centrigrams |
| CGL | 100 Gallons |
| cgm | centigram |
| CGS | Centimeter Gram Second |
| cgs | centimetre-gram-second [cf. fps and mks] |
| CGT | Compensated Gross Tonnage |
| CH | Clock Hours |
| CH | Contact Hour |
| CH | Contact Hours |
| CHS | Cylinders, Heads, and Sectors |
| CI | Cubic Inch |
| CI | Cubic Inches |
| CID | Cubic Inch Displacement |
| CIN | Characters per INch |
| CKD | Canada Knock Down |
| CL | CentiLitre |
| CLICK | Creating Literacy In Computer Knowledge |