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
Etymology
Origin of undermine
First recorded in 1300–50; Middle English underminen; see 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.
“As the 2028 Olympic Games in Los Angeles approach, we cannot allow what should be a celebration of honest sporting endeavor to be overshadowed by this cynical attempt to undermine clean sport,” Banka said.
From Los Angeles Times • May 21, 2026
KOF also warned that a stronger Swiss franc, which is commonly viewed as a safe haven currency during periods of geopolitical uncertainty, could further undermine the competitiveness of Swiss exporters.
From The Wall Street Journal • May 18, 2026
The country's defence ministry meanwhile said it would "firmly confront any attempts to undermine the country's security".
From BBC • May 17, 2026
On May 5, Rubio attended a conference at the military’s Southern Command in Miami, where he and military leaders discussed “efforts to counter threats that undermine security, stability and democracy in our hemisphere.”
From Salon • May 12, 2026
No one thought that anything could undermine her self-control, until one day she felt an itching on her back.
From "The House of the Spirits: A Novel" by Isabel Allende
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.
