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1. Lack of an adequate quantity or number
   "the inadequacy of unemployment benefits";
   - insufficiency, deficiency
    
2. A lack of competence
   "juvenile offences often reflect an inadequacy in the parents";
   - insufficiency
    
3. Unsatisfactoriness by virtue of being inadequate
   - inadequateness

Derived forms: inadequacies

Type of: amount, disadvantage, failing, minus, unsatisfactoriness, weakness

Antonym: adequateness