Look up deficiency in Wiktionary, the free dictionary.

A deficiency is generally a lack of something. It may also refer to:

• A deficient number, in mathematics, a number n for which σ(n) < 2n
• Angular deficiency, in geometry, the difference between a sum of angles and the corresponding sum in a Euclidean plane
• Deficiency (graph theory), a property describing how far a given graph is from having a perfect matching
• Deficiency (medicine), including various types of malnutrition, as well as genetic diseases caused by deficiencies of endogenously produced proteins
• A deficiency in construction, an item, or condition that is considered sub-standard, or below minimum expectations
• Genetic deletion, in genetics, also called a deficiency
• A deficiency judgment, in the law of real estate
• A tax deficiency, an amount owed in taxes over and above what has been submitted in payment