a flat

Short definition from Wiktionary

Noun

1. 1
   Alternative spelling of A-flat.
2. 2
   Alternative spelling of A-flat.
3. 3
   A tone one semitone below A, between G and A, denoted A♭.
4. 4
   A key or other mechanism for producing an A-flat.
5. 5
   The key of A-flat major.
6. 6
   Alternative spelling of A-flat.