This word is acceptable for play in the US & UK dictionaries that are being used in the following games:

• Lexulous
• Wordscraper
• Wordosaur

n. The quality or condition of being deficient; incompleteness or inadequacy.

n. A lack or shortage, especially of something essential to health; an insufficiency: a nutritional deficiency.

n. Inadequacy or incompleteness.

n. An insufficiency, especially of something essential to health.

n. The state of being deficient; inadequacy; want; failure; imperfection; shortcoming; defect.

n. The state of being deficient; a lack or failing; a falling short; incompleteness, as of intelligence, attainments, or performance.

n. That in which a person or thing is deficient; an imperfection.

n. Lack of the necessary quantity, number, etc.; inadequacy; insufficiency: as, a deficiency of troops; a deficiency of blood.

n. Absence; loss.

n. lack of an adequate quantity or number

n. the state of needing something that is absent or unavailable

"It has been demonstrated that a blood protein deficiency is the cause of this inherited illness."

excess   

imperfection    deficiency bill    general deficiency bill    deficiency of an algebraical curve   

inadequacy    want    failure    imperfection    shortcoming    defect   

efficiency    immunodeficiency    inefficiency    proficiency    self-sufficiency    sufficiency   

defect    limitation    disorder    failure    want    disturbance    fault    illness    disadvantage    shortcoming