Sentry
来自Big Physics
early 17th century: perhaps from obsolete centrinel, variant of sentinel.
wiktionary
From earlier sentrie, sentery, of uncertain origin. Perhaps an alteration of sentinel or sanctuary; or perhaps from Old French senteret(“a path”), diminutive of sentier, from Medieval Latin semitarius(“a path”).
etymonline
sentry (n.)
1610s, originally "watchtower;" perhaps a shortened variant of sentinel, which had a variant form centrinel (1590s); or perhaps worn down from sanctuary, on notion of "shelter for a watchman." Meaning "military guard posted around a camp" is first attested 1630s. Sentry-box is from 1728.
