expression, godan verb (-su)
A euphemistic, literary expression for having sex; not used in casual conversation.
二人は人目を忍んで情けを交わした。
The two had sexual intercourse in secret.
A clinical, direct term for sexual intercourse, while 情けを交わす is a softer, euphemistic expression.
From 情け (sympathy, affection) + を + 交わす (exchange). The phrase literally means 'exchange affection' and is used euphemistically for sexual intercourse.