noun
lookout; guard; person on watch
Refers to the role or duty of keeping watch, often in a security or surveillance context. Can mean the person assigned to this task or the duty itself.
彼は銀行強盗の見張り役をしていた。
He was acting as the lookout for the bank robbery.
見張り役を交代する時間だ。
It's time to change the guard duty.