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.
Watch; guard. [Obs.] "That princes do keep due sentinel." Bacon.
A marine crab (Podophthalmus vigil) native of the Indian Ocean, remarkable for the great length of its eyestalks; -- called also sentinel crab.
To watch over like a sentinel. "To sentinel enchanted land." [R.] Sir W. Scott.
To furnish with a sentinel; to place under the guard of a sentinel or sentinels.
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