All G&A a/c A/D a/r A/S a/s/l C/A See all meanings Idioms and phrases with a collision training course idiom[ C/U ]   tunes   plural A’s or As in Western new music, the sixth Notice in the scale (= number of notes) that starts on the Observe C, or simply a list of notes based upon this ObserveIn algebra, the letter a in conjunction with various