aa

Short definition from Wiktionary

Noun

1. 1
   A form of lava flow associated with Hawaiian-type volcanoes, consisting of basaltic rock, usually dark-colored with a jagged and loose, clinkery surface. Compare pahoehoe.
2. 2
   Initialism of acetic acid.
3. 3
   Initialism of acting age.
4. 4
   Initialism of alveolar-arterial.
5. 5
   Initialism of aminoacetone.
6. 6
   Initialism of amino acid.
7. 7
   Initialism of approximate absolute.
8. 8
   Initialism of arachidonic acid.
9. 9
   Initialism of armature accelerator.
10. 10
    Initialism of ascending aorta.
11. 11
    Initialism of atomic absorption.
12. 12
    Initialism of author's alteration.
13. 13
    Initialism of average audience.
14. 14
    Abbreviation of adjectives.
15. 15
    Abbreviation of arteries.
16. 16
    A member of Alcoholics Anonymous.
17. 17
    An AA battery (energy-storage device).
18. 18
    Initialism of affirmative action.
19. 19
    Initialism of air armament.
20. 20
    Initialism of air attaché.
21. 21
    Initialism of aircraft apprentice.
22. 22
    Initialism of aircraft artificer.
23. 23
    Initialism of absolute altitude.
24. 24
    Initialism of anti-aircraft.
25. 25
    Initialism of avenue of approach.
26. 26
    Initialism of assembly area.
27. 27
    Initialism of airman apprentice.
28. 28
    Initialism of absolute alcohol.
29. 29
    Initialism of achievement age.
30. 30
    Initialism of acting appointment.
31. 31
    Initialism of adoption agency.
32. 32
    Initialism of armament artificer.
33. 33
    Initialism of athletic association.
34. 34
    Initialism of author's alteration.
35. 35
    Initialism of aviation annex.
36. 36
    Initialism of angular aperture.
37. 37
    Initialism of amino acid.
38. 38
    Initialism of aminoacyl.
39. 39
    Initialism of acetic acid.
40. 40
    Initialism of acrylic acid.
41. 41
    Initialism of amyloid A.
42. 42
    Initialism of arachidonic acid.
43. 43
    Initialism of ascorbic acid.
44. 44
    Initialism of asymmetric aminohydroxylation.
45. 45
    Initialism of acetaldehyde adduct.
46. 46
    Initialism of adrenal androgen.
47. 47
    Initialism of antiandrogen.
48. 48
    Initialism of antioxidant activity.
49. 49
    Initialism of atomic absorption.
50. 50
    Initialism of activated alumina.
51. 51
    Initialism of anti-antibody.
52. 52
    Initialism of ascending aorta.
53. 53
    Initialism of abdominal aorta.
54. 54
    Initialism of aortic arch.
55. 55
    Initialism of acute appendicitis.
56. 56
    Initialism of allergic asthma.

Adjective

1. 1
   Initialism of arctic-alpine.
2. 2
   Initialism of always afloat.
3. 3
   Abbreviation of ana (“of each, equal parts”).

Pronoun

1. 1
   I.

Symbol

1. 1
   Symbol for attoampere, an SI unit of electrical current equal to 10⁻¹⁸ amperes.
2. 2
   Symbol for the abampere, a CGS unit of electrical current equal to 10 amperes.