aa in English
- AA⇄AA(no periods),
an abbreviation or symbol for the following:
1. achievement age.
2. air-to-air.
3. antiaircraft.
4. author's alteration.
5. (in financial rating) the second highest rank.
6. the second in a s - aa⇄aa, noun.
lava hardened into a rough, slaggy, brittle mass.