All G&A a/c A/D a/r A/S a/s/l C/A See all meanings Idioms and phrases on a collision training course idiom[ C/U ]   audio   plural A’s or As in Western music, the sixth note in the dimensions (= number of notes) that starts around the Take note C, or simply a list of notes determined by this note⟨a⟩ is definitely the 3rd-most-generally made