AC

1. Air conditioning
2. Alternating current 
3. Atlantic City
4. Air Canada
5. Adenylate cyclase
6. Actinium
7. Adenylate cyclase
8. Alternating current
9. Anticipated convection
10. Artificial consciousness
11. Axiom of choice
12. Altocumulus
13. Atlantic City
14. Authorization certificate 
15.  Aelod y Cynulliad
16. Aircraftman
17. AC Comics
18. Adult contemporary music
19. After Colony
20. American Capitalist
21. Anal Cunt
22. Armor Class
23. Ace Combat
24. Armored Core
25. Asheron's Call
26. Assassin's Creed
27. Assault Cube
28. Animal Crossing
29. Arkham City
30. Athletics Canada
31. AC Cars
32. Action Congress
33. Air Canada
34. Alternative for Change (Alternativa por el Cambio
35. Associated Content
36. Australia Council
37. Ayala Corporation 
38. Acre
39. Appeal cases
40. Anarcho-capitalism
41. Ante Christum
42. Anthrocon
43. Assessment center
44. Average cost