Definition of あう
- (v5u, vi) to come together; to merge; to unite; to meet
to fit; to match; to suit; to agree with; to be correct
This white coat will look very nice on you.
- to be profitable; to be equitable
(suf, v5u) (after the -masu stem of a verb) to do ... to each other; to do ... together
The two ladies smiled at each other.