undermine
Americanverb (used with object)
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to injure or destroy by insidious activity or imperceptible stages, sometimes tending toward a sudden dramatic effect.
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to attack by indirect, secret, or underhand means; attempt to subvert by stealth.
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to make an excavation under; dig or tunnel beneath, as a military stronghold.
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to weaken or cause to collapse by removing underlying support, as by digging away or eroding the foundation.
verb
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(of the sea, wind, etc) to wear away the bottom or base of (land, cliffs, etc)
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to weaken gradually or insidiously
their insults undermined her confidence
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to tunnel or dig beneath
Other Word Forms
- underminer noun
Etymology
Origin of undermine
First recorded in 1300–50; Middle English underminen; under-, mine 2
Explanation
To undermine literally means to dig a hole underneath something, making it likely to collapse. But we more often use the word to describe sabotage or the act of weakening someone else's efforts. Originally spelled with a ‘y’ instead of an ‘i’, undermine has Germanic roots and means "to weaken, hinder, or impair." Accidentally undermine the foundation of a house by digging a tunnel to China beneath it and you might be forgiven. Undermine your teacher’s authority by speaking out of turn and throwing spitballs and odds are you’ll get in trouble.
Vocabulary lists containing undermine
The Crucible
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The SAT: Words to Capture Tone, List 4
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Grade 9, List 2
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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.
Critics say such outcomes undermine Polymarket’s claim to be a “truth machine” that harnesses the wisdom of the crowd to generate accurate forecasts of political events.
From The Wall Street Journal • Apr. 11, 2026
To hide the president’s residence would undermine its purpose.
From The Wall Street Journal • Apr. 10, 2026
Iran and Pakistan, which helped with negotiations and will host talks between the U.S. and Iran over the weekend, say those attacks undermine efforts for a truce.
From Barron's • Apr. 9, 2026
Successfully prosecuted cases of the most egregious offenders are a deterrent, and when government resources to enforce the laws are weakened, “it has to undermine confidence in the tax system.”
From Barron's • Apr. 9, 2026
On small things I was thrifty enough; no expenditures on “carousing,” flashy clothes, or any of the other indulgences that are often smugly believed to undermine the budgets of the poor.
From "Nickel and Dimed: On (Not) Getting By in America" by Barbara Ehrenreich
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.
