1. Air Traffic Control
2. Air Training Command
3. Army Training Center
4. ATLAS-COPCO
5. Applied Technology Council - also APT
6. Around-the-clock
7. Absolute Time Command
8. Adiabatic Toroidal Compressor
9. Active Thermal Control
10. Automatic tube compensation
11. Athletic Trainer Certified
12. Adaptive Transform Coding
13. Aberdeen Test Center
14. Address Translation Cache
15. Advanced Technology Center
16. Afghan Technical Consultants
17. Advanced Technical Center
18. Advanced Thermo Concept
19. Air Target Chart
20. Anhydrotetracycline - also AHTC
21. Aspartate transcarbamylase - also ATCase
22. Aviation Training Center - also AVTRACEN
23. Anaplastic thyroid carcinomas - also ATCs
24. Acetylthiocholine - also ATCh
25. Air traffic controllers - also ATCs
26. At-The-Closing order (Lệnh giao dịch tại mức giá khớp lệnh

xác định giá đóng cửa)