deficiency

Noun

Synonyms: lack want insufficiency inadequacy

WordNet 3.0

Noun (2)

the state of needing something that is absent or unavailable“there is a serious lack of insight into the problem”“water is the critical deficiency in desert regions”“for want of a nail the shoe was lost”Synonyms: lack want
lack of an adequate quantity or number“the inadequacy of unemployment benefits”Synonyms: insufficiency inadequacy

Webster's Dictionary (GCIDE)

Deficiency \De*fi"cien*cy\, n.; pl. Deficiencies. [See Deficient.] The state of being deficient; inadequacy; want; failure; imperfection; shortcoming; defect. "A deficiency of blood." --Arbuthnot. [1913 Webster]

[Marlborough] was so miserably ignorant, that his deficiencies made him the ridicule of his contemporaries. --Buckle. [1913 Webster]

Deficiency of a curve (Geom.), the amount by which the number of double points on a curve is short of the maximum for curves of the same degree. [1913 Webster]