[ noun ] a person employed to keep watch for some anticipated event <noun.person>
Sentinel \Sen"ti*nel\, v. t. [imp. & p. p. {Sentineled}or {Sentinelled}; p. pr. & vb. n. {Sentineling} or {Sentinelling}.] 1. To watch over like a sentinel. ``To sentinel enchanted land.'' [R.] --Sir W. Scott.
2. To furnish with a sentinel; to place under the guard of a sentinel or sentinels.
Sentinel \Sen"ti*nel\, n. [F. sentinelle (cf. It. sentinella); probably originally, a litle path, the sentinel's beat,, and a dim. of a word meaning, path; cf. F. sente path. L. semita; and OF. sentine, sentele, senteret, diminutive words. Cf. {Sentry}.] 1. One who watches or guards; specifically (Mil.), a soldier set to guard an army, camp, or other place, from surprise, to observe the approach of danger, and give notice of it; a sentry.
The sentinels who paced the ramparts. --Macaulay.
2. Watch; guard. [Obs.] ``That princes do keep due sentinel.'' --Bacon.
3. (Zo["o]l.) A marine crab ({Podophthalmus vigil}) native of the Indian Ocean, remarkable for the great length of its eyestalks; -- called also {sentinel crab}.
One of these, "Mongolian Bactrian" of 1969, stands sentinel at the entrance to the Hirshhorn show, and looks almost as shockingly incongruous (and droll) now as it did when it was made.