from The American Heritage® Dictionary of the English Language, 4th Edition

  • adj. Lacking an essential quality or element: deficient in common sense.
  • adj. Inadequate in amount or degree; insufficient: a deficient education.

from Wiktionary, Creative Commons Attribution/Share-Alike License

  • adj. Lacking something essential; often construed with in.
  • adj. Insufficient or inadequate in amount.

from the GNU version of the Collaborative International Dictionary of English

  • adj. Wanting, to make up completeness; wanting, as regards a requirement; not sufficient; inadequate; defective; imperfect; incomplete; lacking

from The Century Dictionary and Cyclopedia

  • Lacking; wanting; incomplete.
  • Defective; imperfect; inadequate: as, deficient strength.
  • Not having a full or adequate supply: as, the country is deficient in the means of carrying on war.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

  • adj. of a quantity not able to fulfill a need or requirement
  • adj. falling short of some prescribed norm
  • adj. inadequate in amount or degree


Latin dēficiēns, dēficient-, present participle of dēficere, to fail, be wanting; see defect.
(American Heritage® Dictionary of the English Language, Fourth Edition)
From Latin deficiens, present participle of deficere ("to lack, fail, be wanting"); see defect. (Wiktionary)



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