- noun a serviceman or servicewoman assigned to guard a military base or installation
- noun a soldier assigned to watch for any approaching enemy, while others rest or carry out other tasks
- noun (written as Sentry)an American-designed E-3 airborne warning and control system (AWACS) aircraft
Origin & History of “sentry”
Sentry is probably short for the now obsolete centrinell ‘sentry’. this first appeared in the 16th century as a variant of sentinel (16th c.), which came via French sentinelle from Italian sentinella. It is not altogether clear where the Italian noun came from, but it may well have been derived from the verb sentire ‘perceive, watch’, a descendant of Latin sentīre ‘feel’ (from which English gets sense, sentence, sentiment, etc).