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 course idiom[ C/U ]   music   plural A’s or As in Western new music, the sixth note in the size (= series of notes) that begins within the Take note C, or even a list of notes based on this noteA is often used to denote a thing or a person of an even better or