[dih-fish-uh nt]


lacking some element or characteristic; defective: deficient in taste.
insufficient; inadequate: deficient knowledge.


a person who is deficient, especially one who is mentally defective.

Origin of deficient

1575–85; < Latin dēficient- (stem of dēficiēns, present participle of dēficere to fail, run short, lack, weaken), equivalent to dē- de- + fic-, combining form of facere to make, do1 + thematic -i- + -ent- -ent
Related formsde·fi·cient·ly, adverbnon·de·fi·cient, adjectivenon·de·fi·cient·ly, adverbpre·de·fi·cient, adjectivepre·de·fi·cient·ly, adverbun·de·fi·cient, adjectiveun·de·fi·cient·ly, adverb Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

Examples from the Web for deficient

Contemporary Examples of deficient

Historical Examples of deficient

  • Sometimes he is sure she is deficient in understanding, and at others that her temper only is in fault.

    Lady Susan

    Jane Austen

  • Sir John was not, on his side, deficient in attention to his own interests.

  • By that good lady the Houris are said to be held in deficient esteem.

  • Not to be deficient in interest, Clennam asked what he might be doing there?

    Little Dorrit

    Charles Dickens

  • He might as well say that John Bunyan was deficient in ethical instincts.

    Alarms and Discursions

    G. K. Chesterton

British Dictionary definitions for deficient



lacking some essential; incomplete; defective
inadequate in quantity or supply; insufficient
Derived Formsdeficiently, adverb

Word Origin for deficient

C16: from Latin dēficiēns lacking, from dēficere to fall short; see defect
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 deficient

1580s, from Latin deficientem (nominative deficiens), present participle of deficere "to desert, revolt, fail," from de- "down, away" (see de-) + facere "to do, perform" (see factitious).

Online Etymology Dictionary, © 2010 Douglas Harper

Medicine definitions for deficient




Lacking an essential quality or element.
Inadequate in amount or degree; insufficient.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.