a person or thing that watches or stands as if watching.
a soldier stationed as a guard to challenge all comers and prevent a surprise attack: to stand sentinel.
Digital Technology. tag1(def 9a).

verb (used with object), sen·ti·neled, sen·ti·nel·ing or (especially British) sen·ti·nelled, sen·ti·nel·ling.

to watch over or guard as a sentinel.

Origin of sentinel

1570–80; < Middle French sentinelle < Italian sentinella, derivative of Old Italian sentina vigilance (Latin sent(īre) to observe) + -īna -ine2)
Related formssen·ti·nel·like, adjectivesen·ti·nel·ship, nounun·sen·ti·neled, adjectiveun·sen·ti·nelled, adjective

Synonyms for sentinel Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

Related Words for sentinel

lookout, keeper, guard, protector, picket

Examples from the Web for sentinel

Contemporary Examples of sentinel

Historical Examples of sentinel

  • Like a sentinel on that solitary plain it overwhelms me with a sense of mystery.

    Ballads of a Bohemian

    Robert W. Service

  • After that, we were allowed to come on deck singly, only, and then under a sentinel's charge.

    Ned Myers

    James Fenimore Cooper

  • Neither of the lads so much as glanced at the sentinel as they strolled past him.

  • He did not care, now, if he were halted by a British picket or sentinel.

    The Dare Boys of 1776

    Stephen Angus Cox

  • This would be difficult, for the reason that there was a sentinel on the deck.

    The Dare Boys of 1776

    Stephen Angus Cox

British Dictionary definitions for sentinel



a person, such as a sentry, assigned to keep guard
computing a character used to indicate the beginning or end of a particular block of information

verb -nels, -nelling or -nelled (tr)

to guard as a sentinel
to post as a sentinel
to provide with a sentinel

Word Origin for sentinel

C16: from Old French sentinelle, from Old Italian sentinella, from sentina watchfulness, from sentire to notice, from Latin
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Word Origin and History for sentinel

1570s, from Middle French sentinelle (16c.), from Italian sentinella "a sentinel." OED says "No convincing etymology of the It. word has been proposed," but perhaps (via a notion of "perceive, watch"), from sentire "to hear," from Latin sentire "feel, perceive by the senses" (see sense (n.)).

Online Etymology Dictionary, © 2010 Douglas Harper