| Acronym | Definition |
|---|
| CLASS | Classic(al) |
| CLASS | Classified |
| CLASS | Community Living Assistance Services and Supports (Act) |
| CLASS | Celecoxib Long-Term Arthritis Safety Study |
| CLASS | College of Letters Arts and Social Sciences |
| CLASS | Customer Local Area Signal System |
| CLASS | Community Living Assistance and Support Services |
| CLASS | Comprehensive Large Array Data Stewardship System |
| CLASS | Celebrating Loyalty and Achievement for Staying in School (award) |
| CLASS | Consular Lookout And Support System |
| CLASS | Canadian Land Surface Scheme |
| CLASS | Canadian Laser Aesthetic Surgery Society |
| CLASS | Cross-Chain Loran Atmospheric Sounding System |
| CLASS | Cooperative Library Agency for Systems and Services |
| CLASS | Centralized Local Area Selective Signaling |
| CLASS | Client Access to Systems and Services |
| CLASS | Close Air Support System |
| CLASS | Coalition of Law Abiding Sporting Shooters (Australia) |
| CLASS | Continuum and Line Analysis Single-Dish Software |
| CLASS | Class-Christian Liberty Academy School System |
| CLASS | Closed Loop Artillery Simulation System |
| CLASS | Clinical Anatomy Interactive Lesson |
| CLASS | Come Late and Start Sleeping |
| CLASS | Communications Link Analysis and Simulation System |
| CLASS | CAST Lesson Authoring System |
| CLASS | Carrier Landing Aid Stabilization System |
| CLASS | Composite Lightweight Affordable Spacecraft Structure |
| CLASS | Children Learning About Space Science (NASA) |
| CLASS | Communication Link Analysis and Simulation System |
| CLASS | Central Leatherstocking Area Sighthound Society (Starkville, NY) |
| CLASS | Customized Local Area Signaling Service (telecommunications) |
| CLASS | Customer Local Area Signal(ing) Service |
| CLASS | College Level Assessment and Survey Services |
| CLASS | Java Intermediate Compiled Bytecode (file extension) |
| CLASS | Custom Local Area Subscriber Service (ITI) |
| CLASS | Consolidated Loan Administration and Servicing System |
| CLASS | Computerized Labeling And Address Sequence System |
| CLASS | Cross-Layer Signaling Shortcut |
| CLASS | Centralized Line Access Switch System |
| CLASS | Classroom Listening and Scoring System |