| Abbreviation | Definition |
|---|---|
| CLM | Countway Library of Medicine |
| CLMS | Central Library Main Shelves |
| CLMT | Collaborative Learning Management Tool |
| CLN | Class Library For Numbers |
| CLOCKSS | Controlled Lots Of Copies Keep Stuff Safe |
| CLONE | Cooperating Libraries Of Nash and Edgecombe |
| CLOUD | Communities and Libraries Online Union Database |
| CLP | Carnegie Library of Pittsburgh |
| CLP | Carnegie Library of Pittsburgh's |
| CLQ | Chemical Library Query |
| CLR | Council on Library Resources |
| CLRE | Consuls of the Later Roman Empire |
| CLSA | California Library Services Act |
| CLSB | California Library Services Board |
| CLSP | Collaborative Library Services Platform |
| CLUE | Computerized Library User Education |
| CLUG | Cochrane Library Users Group |
| CLUT | Color Look-Up Table |
| CMAJ | Canadian Medical Association Journal |
| CMCL | Cape May County Library |