互いに〜する
to do (something) to each other
of two people, to glare at one other
to do something together with someone else
to keep each other in countenance―practise log-rolling 【イディオム・格言的には:】“Roll my log, and I'll roll yours.”
to joke with each other
the act of biting each other
to feel mutually ill at ease with each other
the condition of being in harmony with something
to compete with someone
to get along well with each other
family relations that hate each other
the condition of doing something with the mutual understanding of another party