suffix, godan verb (-u)
pass each other; mingle; exchange
Suffix-like verb attached to the -masu stem of another verb, indicating mutual or reciprocal action. Common in compounds like 行き交う (come and go), 飛び交う (fly about), 話し交う (talk together). Not used as a standalone verb in modern Japanese.
駅前では多くの人が行き交っている。
Many people are coming and going in front of the station.
部屋の中では楽しそうな笑い声が飛び交っていた。
Joyful laughter was flying about in the room.