noun (n)

• the state of needing something that is absent or unavailable(noun.state)

  Example:
  Water is the critical deficiency in desert regions.
  

  Synonym:
  lack, want
  

  source: wordnet30
• lack of an adequate quantity or number(noun.attribute)

  Synonym:
  inadequacy, insufficiency
  Antonym:
  adequacy, sufficiency
  

  source: wordnet30
• The state of being deficient; inadequacy; want; failure; imperfection; shortcoming; defect.(noun)

  source: webster1913