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[uhn-der-mahyn or especially for 1, 2, 4, uhn-der-mahyn] /ˌʌn dərˈmaɪn or especially for 1, 2, 4, ˈʌn dərˌmaɪn/
verb (used with object), undermined, undermining.
to injure or destroy by insidious activity or imperceptible stages, sometimes tending toward a sudden dramatic effect.
to attack by indirect, secret, or underhand means; attempt to subvert by stealth.
to make an excavation under; dig or tunnel beneath, as a military stronghold.
to weaken or cause to collapse by removing underlying support, as by digging away or eroding the foundation.
Origin of undermine
1300-50; Middle English underminen. See under-, mine2
Related forms
underminer, noun
underminingly, adverb Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2015.
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Examples from the Web for undermining
Contemporary Examples
Historical Examples
  • The Turks were undermining the town, and countermines had to be prepared.

    The Strange Story Book Mrs. Andrew Lang
  • Yet, were I to show the least energy or activity in support of the King's authority, I should then be accused of undermining it.

    The Secret Memoirs of Louis XV./XVI, Complete Madame du Hausset, an "Unknown English Girl" and the Princess Lamballe
  • The gateway of the middle ward was overthrown by undermining, part of it has sunk and moved out of the perpendicular.

    British Castles Charles H. Ashdown
  • They begin by undermining the trust you feel in your own claims.

    Too Old for Dolls Anthony Mario Ludovici
  • It appealed to the highest form of self-sacrifice; it arrayed itself against a vice which was undermining society.

British Dictionary definitions for undermining


verb (transitive)
(of the sea, wind, etc) to wear away the bottom or base of (land, cliffs, etc)
to weaken gradually or insidiously: their insults undermined her confidence
to tunnel or dig beneath
Derived Forms
underminer, noun
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition
© William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins
Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012
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Word Origin and History for undermining



c.1300, undermyne, from under + mine (v.). The figurative sense is attested from early 15c. Cf. Dutch ondermijnen, Danish underminere, German unterminiren. Related: Undermined; undermining.

Online Etymology Dictionary, © 2010 Douglas Harper
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