expression, zuru verb
communicate secretly; form a close friendship
A literary set phrase used for secret communication or forming a close, often conspiratorial, bond. The zuru verb form is a classical alternative to 款を通じる.
敵と款を通ずる行為は反逆とみなされた。
The act of secretly communicating with the enemy was considered treason.
彼は裏で競合他
He was secretly in league with a rival company behind the scenes.