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See also: Sentinel



1570s, from Middle French sentinelle, from Old Italian sentinella (perhaps via a notion of "perceive, watch", compare Italian sentire (to feel, hear, smell)), from Latin sentiō (feel, perceive by the senses). See sense.


  • IPA(key): /ˈsɛntɪnəl/
  • (file)


sentinel (plural sentinels)

  1. A sentry, watch, or guard.
  2. (obsolete) A private soldier.
    • 1789, John Moore, Zeluco, Valancourt 2008, p. 33:
      “I will not permit the poorest centinel to be treated with injustice.”
  3. (computer science) a unique string of characters recognised by a computer program for processing in a special way; a keyword.
    The <xmp> tag is a sentinel that suspends web-page processing and displays the subsequent text literally
  4. A sentinel crab.
  5. (attributive, medicine, epidemiology) A sign of a health risk (e.g. a disease, an adverse effect).
    sentinel animals can be used to explore endemic diseases.



sentinel (third-person singular simple present sentinels, present participle (US) sentineling or (UK) sentinelling, simple past and past participle (US) sentineled or (UK) sentinelled)

  1. (transitive) To watch over as a guard.
    He sentineled the north wall.
  2. (transitive) To post as guard.
    He sentineled him on the north wall.
  3. (transitive) To post a guard for.
    He sentineled the north wall with just one man.
    • 1873, Harper's New Monthly Magazine (volume 46, page 562)
      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 []