thicken
Americanverb (used with or without object)
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to make or become thick or thicker.
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to make or grow more intense, profound, intricate, or complex.
The plot thickens.
verb
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to make or become thick or thicker
thicken the soup by adding flour
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(intr) to become more involved
the plot thickened
Other Word Forms
Derived Forms
Inflected Forms
Participles
Conjugated Forms
Present
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thickensimple
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thickenssimple
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have thickenedperfect
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has thickenedperfect
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am thickeningprogressive
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are thickeningprogressive
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is thickeningprogressive
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have been thickeningperfect progressive
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has been thickeningperfect progressive
Past
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thickenedsimple
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had thickenedperfect
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was thickeningprogressive
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were thickeningprogressive
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had been thickeningperfect progressive
Future
Etymology
Origin of thicken
1375–1425; late Middle English thiknen < Old Norse thykkna. See thick, -en 1
Explanation
To thicken is to become denser or to make something thicker. When you accidentally burn dinner, the smoke in the kitchen thickens. Time to get the fire extinguisher. There are two ways to thicken: to become thick or to make thick. Cooks often use flour or cornstarch to thicken sauces. And when you add flour to your brownie batter, you thicken it. An earlier, now obsolete meaning was "to crowd together." The phrase "the plot thickens" means that a situation is becoming more and more complicated or interesting.
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:
As the valve tissue degenerates, the thin flaps that should meet neatly can thicken, stretch, or lose their normal shape.
From Science Daily ● Jul. 12, 2026
The sauce is then finished with soy sauce, rice vinegar, sugar and chili paste along with a cornstarch slurry to thicken it.
From Salon ● Jun. 28, 2026
Activated by the hormones of the menstrual cycle, these sores thicken and bleed each month, inflaming and scarring the surrounding tissue.
From BBC ● Jun. 1, 2026
At the same time, M proteins can also cause the blood to thicken and concentrate in urine, both of which can cause renal problems.
From Slate ● Mar. 29, 2026
I tried to throw myself at it again, but Clancy’s hand lashed out to snatch my wrist, and I felt every muscle in my body thicken to stone.
From "The Darkest Minds" by Alexandra Bracken
When stirred through at the end, it thickens the tomato juices into something cohesive — salty, tangy, faintly luxurious.
From Salon ● Mar. 23, 2026
Few writers since Henry James can create an atmosphere of doubt around events and character as effectively as this author does, and in “Venetian Vespers” the miasma thickens at every turn.
From The Wall Street Journal ● Oct. 9, 2025
But keep your whisk moving, and you’ll feel it: the moment the sauce thickens, holds, and gleams just slightly.
From Salon ● Jun. 5, 2025
But it’s worthwhile hanging in: As the chapters unfold, the plot thickens.
From Los Angeles Times ● Mar. 28, 2025
As you head south, toward Zaire, the land rises and forms hills, and the forest begins to spread away from the rivers and thickens into a closed canopy, and you enter the rain forest.
From "The Hot Zone" by Richard Preston
Since that incident, Gen Bewick says Akrotiri's air defences have been "thickened".
From BBC ● Mar. 30, 2026
What’s different now is that artificial intelligence has thickened the plot.
From Barron's ● Mar. 5, 2026
"This thickened, heated crust may have made the region mechanically weaker, so that the plate boundary preferentially shifted here," explains co-author PD Dr. Jörg Geldmacher, marine geologist at GEOMAR.
From Science Daily ● Feb. 23, 2026
To get older, wiser and have your skin thickened by all the slings and arrows?
From The Wall Street Journal ● Feb. 18, 2026
The truck backed sturdily up Carmel Hill and it got past the Jack’s Peak road and was just going into the last and steepest pull when the motor’s breathing thickened, gulped, and strangled.
From "Cannery Row" by John Steinbeck
The results broadened the concern beyond isolated thickening of the mitral valve, although animal findings cannot determine what happens in people taking standard doses of antidepressants.
From Science Daily ● Jul. 12, 2026
On a humbler scale, Kail poetically marks the passage of time with a thickening palm tree.
From Los Angeles Times ● Jul. 9, 2026
For hypertrophic cardiomyopathy—the thickening of heart muscles—it was 56 steps.
From The Wall Street Journal ● Apr. 19, 2026
“Let the pie cool completely before slicing. This allows the filling to finish thickening and gives you the best pie-eating experience.”
From Salon ● Jan. 30, 2025
They curled about his body, thickening and hardening into bark.
From "The Last Olympian" by Rick Riordan
Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023
Idioms from The American Heritage® Idioms Dictionary copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.
