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 system idiom[ C/U ]   new music   plural A’s or As in Western new music, the sixth Observe in the size (= number of notes) that starts within the Be aware C, or a list of notes based upon this Observe?a? would be the 3rd-most-typically made use of letter in Eng