Definition of sentinel in US English:



  • 1A soldier or guard whose job is to stand and keep watch.

    • ‘By the third week the men practiced guard duty, receiving instructions on walking their posts and performing interior and exterior guard duty, and learning the general and specific orders of a sentinel posted for guard duty.’
    • ‘There has been some speculation that Charles was assassinated, but from forensic examination of his skull it is fairly certain that an enemy sentinel caught sight of his head peering over the parapet and managed a lucky hit.’
    • ‘A sentinel stood on top of the wall, an easy target.’
    • ‘Flanking the elevator on both sides stood the Shadow Lord's black-garbed sentinels, his sinister Warrior disciples.’
    • ‘The sentinel stood lounging by the shaft that led down into the underground labor system.’
    • ‘A soldier high on the roof behind his machine gun watched vigilantly over the far horizon - a silent sentinel.’
    • ‘The sentinel still stood at attention directly under the lantern, not moving but to breathe.’
    • ‘So say the sentinels guarding the long coastline of the country this weekend.’
    • ‘Take out the launchers as quickly as possible, then wipe out the remaining soldiers and sentinels with your mutant powers.’
    • ‘Men who have merited this last distinction are to be suffered to pass all guards and sentinels which officers are permitted to do.’
    • ‘A lone sentinel stood in the middle of the roadway to the castle standing on the hill.’
    • ‘After walking down a short hall another door came into view; this one had only one sentinel.’
    • ‘She knew not whether to fear it or love it; at this moment she only wished to find someplace where she could sit, unnoticed by the sentinel who stood near the fire at the east end of the encampment.’
    • ‘Immediately, a sentinel standing guard near the jail confronted him.’
    • ‘Four silent sentinels still mounted guard at each point of the coffin but the long queues of visitors had gone.’
    • ‘A group of sentinels stood to stop the elated pilots, but were gunned down with one well-placed salvo from the Omegas.’
    • ‘The sentinels who had stood watch throughout the night before watched those roadside dwellers with weary but alert eyes, should they suddenly decided to start a riot in front of the palace.’
    sentry, security guard, nightwatchman
    View synonyms
    1. 1.1Medicine A thing that acts as an indicator of the presence of disease.
      as modifier ‘a sentinel surveillance program for influenza’
      • ‘The beetles' affinity for certain trees, like maples, poplars, willows, and elms, is significant because such attractive species may be used as sentinel trees.’
      • ‘Surveillance for West Nile is also conducted by testing pools of mosquitoes and flocks of sentinel chickens.’
      • ‘Amphibians are regarded as sentinel vertebrates in the current drama of global extinctions.’
      • ‘We here present a model of field study, based on the use of sentinel species, that we are currently applying to risk assessment in the area around a focus of pollution.’
      • ‘Performing sentinel lymph node biopsy requires coordinated expertise between nuclear medicine physicians, pathologists, and surgeons.’


[with object]
  • Station a soldier or guard by (a place) to keep watch.

    ‘a wide course had been roped off and sentineled with police’
    figurative ‘trees sentineled the trenches’


  • stand sentinel

    • (of a soldier) keep watch.

      ‘soldiers stood sentinel with their muskets’
      figurative ‘a tall round tower standing sentinel over the river’
      • ‘Survivors of the old forest still stand sentinel among the rocks, which are cross-hatched, swirled, puckered, potholed, or sometimes as smooth as slickrock.’
      • ‘I recall the scepticism with which my grandfather would make me stand sentinel at the gatepost to keep a sharp eye on the milkman, because he was suspected of adding water to milk.’
      • ‘A dead 130-year-old cedar still stands - an eloquent, natural piece of garden art left to stand sentinel.’
      • ‘Several barriers in his consciousness that normally stand sentinel around his impressions of women become pliable and my image begins to migrate towards that of his mother.’
      • ‘Twelve red pillars, like sons of Jacob or apostles of Jesus sprinkled with the blood of the sacrifice, stand sentinel around four red and gold pillars in the center.’
      • ‘Windmills, which still stand sentinel above the plains of La Mancha, become ‘monstrous giants’ against whom battles must be fought in the name of honour.’
      • ‘At low elevations, charred trunks today stand sentinel on steep slopes where fire burned very hot, consuming every needle and pine cone.’
      • ‘The oil towers stand sentinel, bone-empty, in the dark.’
      • ‘Unfortunately for Peter, another beefy guard, indistinguishable from the rest, stood sentinel outside the door.’
      • ‘Jess ran after the boys as they made a headway towards the entrance where a guard stood sentinel.’


Late 16th century: from French sentinelle, from Italian sentinella, of unknown origin.