[ in-ef-i-kuh-see ]
/ ɪnˈɛf ɪ kə si /


lack of power or capacity to produce the desired effect.

Nearby words

  1. ineffable,
  2. ineffaceable,
  3. ineffective,
  4. ineffectual,
  5. inefficacious,
  6. inefficiency,
  7. inefficient,
  8. inegalitarian,
  9. inelastic,
  10. inelastic collision

Origin of inefficacy

From the Late Latin word inefficācia, dating back to 1605–15. See in-3, efficacy Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

Examples from the Web for inefficacy

Word Origin and History for inefficacy



"want of force or virtue to produce the desired effect," 1610s, from Late Latin inefficacia, from inefficacem (nominative inefficax), from in- "not, opposite of" (see in- (1)) + efficax (see efficacy).

Online Etymology Dictionary, © 2010 Douglas Harper