[ 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), un·der·mined, un·der·min·ing.

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.

Nearby words

  1. underling,
  2. underlit,
  3. underlying,
  4. undermanned,
  5. undermentioned,
  6. undermining ulcer,
  7. undermodulate,
  8. undermost,
  9. underneath,
  10. undernourish

Origin of undermine

First recorded in 1300–50, undermine is from the Middle English word underminen. See under-, mine2

Related formsun·der·min·er, nounun·der·min·ing·ly, adverb

Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

Examples from the Web for undermine

British Dictionary definitions for undermine


/ (ˌʌndəˈmaɪn) /

verb (tr)

(of the sea, wind, etc) to wear away the bottom or base of (land, cliffs, etc)
to weaken gradually or insidiouslytheir insults undermined her confidence
to tunnel or dig beneath
Derived Formsunderminer, 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

Word Origin and History for undermine



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