noun: sentinel; plural noun: sentinels
1.a soldier or guard whose job is to stand and keep watch.“soldiers stood sentinel with their muskets”
2.Medicinean indicator of the presence of disease.“the first national HIV sentinel surveillance programme in the developing world”
verb: sentinel; 3rd person present: sentinels; past tense: sentinelled; past participle: sentinelled; gerund or present participle: sentinelling; past tense: sentineled; past participle: sentineled; gerund or present participle: sentineling
1.station a soldier or guard by (a place) to keep watch.“a wide course had been roped off and sentinelled with police”
late 16th century: from French sentinelle, from Italian sentinella, of unknown origin.