deficiency
Pluraldeficiencies
- 1A shortage or insufficiency of something, especially of a nutrient or other element essential to health.
Like an engine running low on oil: it keeps going for a while, but damage builds up unseen.
Blood tests revealed a serious iron deficiency that explained her constant fatigue.
Children raised on that limited diet often develop vitamin deficiencies.
Similarshortage, lack, insufficiency, deficit
Note
Here the word becomes countable and specific: someone can have a deficiency, or several deficiencies. In talk of health and diet, the missing thing usually comes first as a modifier, as in iron deficiency or vitamin deficiencies, rather than after of. Outside medicine it can name any particular weakness. The Economist in 2013 counted among academia's deficiencies the scarcity of women in its higher echelons.
- 2The condition of being inadequate or incomplete; a falling short of what is needed or expected.
The audit exposed deficiency in the company's record-keeping practices.
Critics pointed to general deficiency in the proposal's reasoning.
Similarinadequacy, insufficiency, weakness, imperfection
Oppositeadequacy, sufficiency
Note
English built this word from deficient plus the suffix -cy, much as Latin formed dēficientia, and every later sense keeps that idea of falling short. Used as a mass noun, it names a general condition, as in deficiency in record-keeping. When it takes an article or a plural, it usually points to one particular gap, which is the territory of the countable shortfall.
- 3In geometry, the amount by which a curve's number of double points falls short of the maximum possible for curves of the same degree.
The deficiency tells us how many double points the curve lacks relative to others of its degree.
Computing the deficiency requires comparing the curve's double points with the theoretical maximum.
Note
The everyday idea of falling short becomes a whole number here. A curve of a given degree can carry only so many double points, and this figure records how many it lacks. Geometry also uses the word for the linear-system measure. This one counts points on a single curve, so asking whether the subject is curves or linear systems tells the two apart.
- 4In geometry, the codimension of a linear system within the corresponding complete linear system: how many dimensions it falls short of the full system.
When the deficiency is zero, the linear system is complete.
Algebraic geometers compute the deficiency to measure how far a system sits inside its complete counterpart.
Note
Linear systems have their own shortfall, measured in dimensions rather than points. The figure says how far a system sits below the complete linear system that contains it, so a value of zero means the system is already complete. Unlike the double-point count, it describes a whole family of objects rather than a single curve.
Practice
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Origin
Formed from "deficient" plus the suffix "-cy," comparable to Latin "dēficientia."