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 course idiom[ C/U ]   audio   plural A’s or As in Western tunes, the sixth Observe in the scale (= series of notes) that commences over the note C, or possibly a list of notes based upon this Observe?a? could be the 3rd-most-typically made use of letter in En