sentinel

name

1. A place in the United States:
2. A place in the United States:
3. A place in the United States:
4. A place in the United States:

noun

Etymology: First attested in the 1570s from Middle French sentinelle (“watch or guard kept by a soldier”), from Old Italian sentinella, probably from sentina + -ella, from sentire (“perceive, watch, hear”), from sentiō (“feel, perceive by the senses”). See also sense, sentient.

1. A sentry, watch, or guard.

   “They promised faithfully to bear their confinement with patience, and were very thankful that they had such good usage as to have provisions and light left them; for Friday gave them candles (such as we made ourselves) for their comfort; and they did not know but that he stood sentinel over them at the entrance.”

   “the sentinels who paced the ramparts”

2. A private soldier.

   ““I will not permit the poorest centinel to be treated with injustice.””

3. A unique value recognised by a computer program for processing in a special way, or marking the end of a set of data.

   “The <xmp> tag is a sentinel that suspends web-page processing and displays the subsequent text literally”

   “[…] a sentinel value that indicates a missing entry.”

4. A sentinel crab.
5. A sign of a health risk (e.g. a disease, an adverse effect).

   “sentinel animals can be used to explore endemic diseases.”

verb

Etymology: First attested in the 1570s from Middle French sentinelle (“watch or guard kept by a soldier”), from Old Italian sentinella, probably from sentina + -ella, from sentire (“perceive, watch, hear”), from sentiō (“feel, perceive by the senses”). See also sense, sentient.

1. To watch over as a guard.

   “He sentineled the north wall.”

2. To post a guard for.

   “He sentineled the north wall with just one man.”

   “The old-fashioned stoop, with its suggestive benches on either side, lay solitary and silent in the moonlight; the garden path, weedily overgrown since father's death, and sentineled here and there with ragged hollyhock, lay quiet and dew-laden […]”