| Term | Definition |
| C | degress Celsius (Centigrade) |
| c/w | with |
| Ca | calcium |
| CA | cancer |
| cal | calorie |
| cap | capsule |
| CAT | computerized axial tomography |
| Cath | catheter |
| CBC | complete blood count |
| CBET | certified biomedical equipment technician |
| CBR | complete blood rest |
| cc | cubic centimeter |
| CC | chief complaint |
| CCU | coronary care unit, critical care unit |
| CDA | certified dental assistant |
| CDC | Centers for Disease Control & Prevention |
| CEO | chief executive officer |
| CF | cysticfibrosis |
| CHD | coronary heart disease |
| CHF | congestive heart failure |
| CHO | carbohydrate |
| chol | cholesterol |
| CICU | cardiac intensive care unit |
| ck | check |
| Cl | chloride or chlorine |
| cl liq | clear liquids |
| cm | centimeter |
| CMA | certified medical assistant |
| CNP | certified nurse practitioner |
| CNS | central nervous system |
| co, c/o | complains of |
| CO | carbon monoxide, coronary occlusion |