English Reference
noun

deficiency

n.
US /dɪˈfɪʃənsi/ UK /dɪfˈɪʃənsi/ de·fi·cien·cy UK spelling deficiencies

  1. 01 C1 Advanced Technical Medicine

    a lack of something your body needs to stay healthy, like a vitamin.

    an insufficiency of a substance, such as a vitamin or mineral, that is essential for healthy physiological functioning.

    Simple

    A vitamin C deficiency can make you feel very tired and weak.

    In context

    The patient presented with symptoms consistent with a severe iron deficiency, likely exacerbated by a restrictive diet and high physical activity.

    Usage

    Often followed by the preposition 'of'.

  2. 02 C1 Advanced Formal

    a weakness or a way in which something is not good enough.

    a failure to reach a required standard or a specific flaw in a system, plan, or character.

    Simple

    The report pointed out a serious deficiency in the school's safety rules.

    In context

    The audit identified several structural deficiencies in the company's internal accounting procedures that required immediate rectification.

    Usage

    Commonly used in formal reports and academic evaluations.

    shortcomingflawdefect
  3. 03 C2 Proficiency Technical Math

    a specific measurement of how much a mathematical shape or system is missing.

    a technical measure of the amount by which a geometric or linear system falls short of a maximum or complete state.

    Simple

    The professor explained how to calculate the deficiency of the curve.

    In context

    In algebraic geometry, the deficiency of a curve relates to the number of double points compared to the maximum possible for its degree.

Responding to the incident on Tuesday, President Emmerson Mnangagwa described the event as “tragic” and said it exposed serious deficiencies that needed to be addressed immediately.

Al Jazeera· 16 Aug 2026

Responding to the incident last week, President Emmerson Mnangagwa described it as “tragic” and said it exposed serious deficiencies that needed to be addressed immediately.

Al Jazeera· 17 Aug 2026

From deficient + -cy. Compare Latin dēficientia.

Etymology adapted from Wiktionary, available under CC BY-SA 4.0.

This entry
Level C1 · Advanced
Frequency Frequent
Updated