sentinel
Americannoun
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sentinels
plural
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a person or thing that watches or stands as if watching.
The cats were the sentinels of the house, patrolling constantly for rodents, dogs, and other invaders.
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a soldier stationed as a guard to challenge all comers and prevent a surprise attack.
Lincoln refused to make his home mansion a garrison during the Civil War, but plain-clothes sentinels did patrol the property
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Digital Technology. tag.
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Medicine/Medical. an indication or mark that a disease is present or prevalent.
New viruses in the wastewater can be used as sentinels of future outbreaks.
verb (used with object)
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sentinels,
present (3rd person singular)
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sentineled,
past participle, past
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sentinelled,
past participle, past (especially British)
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sentineling,
present participle
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sentinelling
present participle (especially British)
adjective
noun
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a person, such as a sentry, assigned to keep guard
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computing a character used to indicate the beginning or end of a particular block of information
verb
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to guard as a sentinel
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to post as a sentinel
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to provide with a sentinel
Other Word Forms
Derived Forms
Inflected Forms
Nouns
Participles
Conjugated Forms
Present
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sentinelsimple
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sentinelssimple
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have sentineledperfect
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have sentinelledperfect
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has sentineledperfect
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has sentinelledperfect
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am sentinelingprogressive
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am sentinellingprogressive
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are sentinelingprogressive
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are sentinellingprogressive
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is sentinelingprogressive
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is sentinellingprogressive
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have been sentinelingperfect progressive
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have been sentinellingperfect progressive
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has been sentinelingperfect progressive
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has been sentinellingperfect progressive
Past
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sentineledsimple
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sentinelledsimple
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had sentineledperfect
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had sentinelledperfect
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was sentinelingprogressive
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was sentinellingprogressive
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were sentinelingprogressive
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were sentinellingprogressive
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had been sentinelingperfect progressive
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had been sentinellingperfect progressive
Future
Etymology
Origin of sentinel
First recorded in 1570–80; from Middle French sentinelle, from Italian sentinella, derivative of Old Italian sentina “vigilance,” from Latin sent(īre) “to feel” + -īna -ine 2
Explanation
A sentinel is a guard, a lookout, a person keeping watch. It's often a soldier, but not always. If you're watching a pot, waiting for it to boil, you're standing sentinel over it — and incidentally, it won't boil until you leave. Etymologists think sentinel stems from the Old Italian words sentina, meaning "vigilance," and sentire, "to hear or perceive." It's a close cousin of sentry, which means the same thing. You can use sentinel as a noun or a verb. A kid in a snowball war might be the sentinel, patrolling the entrance to the fort. Wolves stand sentinel over their kill, stepping aside only for the alpha male, who always eats first.
Vocabulary lists containing sentinel
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Common Senses: Sent, Sens ("Feel")
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Example Sentences
Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.
See Examples For:
Ahead of our return to the city, we drive back up the ridge, back through Burguete, the inn still shuttered, and up to Roncesvalles, where the old monastery looms like a sentinel over the pass.
From Salon ● Nov. 8, 2025
The church stood empty like a silent sentinel over a small cemetery next to it.
From Slate ● Oct. 24, 2024
Beal noted one of the sentinel signs that a farm has been infected is dead barn cats that have drunk the infected, raw milk.
From Los Angeles Times ● Oct. 4, 2024
The area has been named a sentinel landscape, a federally led effort to promote sustainable land-use practices near military installations.
From Los Angeles Times ● May 23, 2024
All the focus she’d poured into the single sentinel was shunted back into her physical body, and she stumbled and fell, gasping, to her knees.
From "Strange the Dreamer" by Laini Taylor
The birds feed on insects living on rhinos and can also act as sentinels - calling to warn their hosts when danger approaches.
From BBC ● Aug. 25, 2026
“We stand on the walls, sentinels of the inner sanctum, against the assault of AI slop. The Ontology is based firmly in reality—there is, here, a dialectic between ground truth, tribal knowledge, and enhancements.”
From The Wall Street Journal ● May 5, 2026
“We stand on the walls, sentinels of the inner sanctum, against the assault of AI slop,” Karp said in his letter to shareholders.
From Barron's ● May 4, 2026
A few rise above head-height, the most energetic sentinels of regeneration.
From Los Angeles Times ● Mar. 13, 2026
The herons are herons; they don’t turn into Ardea herodias, long-legged waders, azure airborne avians, or sapphire sentinels of the skies.
From "The Sense of Style" by Steven Pinker
As by the elms that line its street, the hills that watch its roofs, Lyme, Conn., is sentineled by artistic good usage, fortressed by aesthetic tradition.
From Time Magazine Archive
It is nature's grand police, vigilant and faithful, sentineled in the soul, guarding against violence to peace and life.
From John Brown An Address at the 14th Anniversary of Storer College by Frederick Douglass
Poor lad! he was coming down the pass last night, not knowing that it was sentineled by the enemy.
From Then Marched the Brave by Anna S. Hicks
A fort, mounting eight guns, sentineled the approach to the city from beneath, while the heights above were guarded by a three-banked battery.
From Sword and Pen Ventures and Adventures of Willard Glazier by John Algernon Owens
He saw that the walls were poorly sentineled, but they were sufficiently high to render an attempt to scale them foredoomed to failure.
From The Chessmen of Mars by Edgar Rice Burroughs
He was stationed at Fort Knox, where he sentinelled the country’s gold reserves.
From The New Yorker ● Mar. 27, 2017
Williamstown, sentinelled with maple trees, smiles at the Berkshires.
From Time Magazine Archive
Across the snow-fields shimmered a translucent rosy glow, so that they seemed no longer bleak and desolate, but lay spread like an unfurled banner of glory betwixt the great peaks which sentinelled them round.
From The Vision of Desire by Margaret Pedler
Above the 'ever loyal city,' rose The surging sound of unloosed tongues and feet, As the encompassed town and suburbs vast, The boated river and the sentinelled bridge Swarmed, parti-colored, with the populace.
From The Continental Monthly , Vol. 2 No. 5, November 1862 Devoted to Literature and National Policy by Various
Nestling in a grove of primeval pines that sentinelled the placid, shining waters of the Don stood a low, wide-eaved cottage.
From The Four Canadian Highwaymen or, The Robbers of Markham Swamp by J. E. (Joseph Edmund) Collins
The two great poplar-trees, sentineling what had once been the gate of the old Gordon homestead, had been spared through all the industrial changes.
From The Quickening by E. M. Ashe
The dry stalks, sentinelling the seared ground, waved their tattered remnants of unpicked bolls to and fro—summer's battle flags which had not yet fallen.
From The Bishop of Cottontown A Story of the Southern Cotton Mills by John Trotwood Moore
The round green hills sentinelling the broad, expansive bosom of the Hudson held her attention by their beauty as the train followed the line of the stream.
From Sister Carrie: a Novel by Theodore Dreiser
Dignity and grace lie in these tall swaying trees sentinelling the way on either side.
From In the Claws of the German Eagle by Albert Rhys Williams
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