| Abbreviation | Definition |
|---|---|
| ASIA | American Sheep Industry Association |
| ASICS | Application Specific Integrated Circuit(s) |
| ASLAP | American Society of Laboratory Animal Practitioners |
| ASM | American Society for Microbiology |
| ASME | American Society of Mechanical Engineers |
| ASPE | Assistant Secretary for Planning and Evaluation |
| ASPER | Assistant Secretary for PERsonnel |
| ASQ | American Society for Quality |
| ASR | Analyte Specific Reagent |
| ASRM | American Society for Reproductive Medicine |
| AST | aspartate aminotransferase |
| ASTHO | Association of State and Territorial Health Officials |
| AT | Acquisitions Team |
| AT | AntiThrombin |
| AT(OC) | Acquisitions Team (OC) |
| ATC | Anatomical Therapeutic Chemical |
| ATM | Automatic Teller Machine |
| ATO | Authorization To Operate |
| ATPA | American Technology Pre-eminence Act of 1991 |
| ATPM | Association of Teachers and Preventive Medicine |