IMPROPER definition: not proper; not strictly belonging, applicable, correct, etc.; erroneous. See examples of improper used in a sentence.

improper adjective (WRONG) unsuitable or not correct for a particular use or occasion: improper prescription of medicines

1. not proper; not strictly belonging, applicable, or correct: drew improper conclusions. 2. not in accordance with propriety or regulations: improper conduct. 3. abnormal; irregular.

Definition of improper adjective in Oxford Advanced Learner's Dictionary. Meaning, pronunciation, picture, example sentences, grammar, usage notes, synonyms and more.

If you describe someone's behaviour as improper, you mean that it is rude or shocking.

unsuitable or inappropriate, as for the purpose or occasion: improper attire for a formal dance. abnormal or irregular: improper functioning of the speech mechanism.

Nov 30, 2025 · improper (comparative more improper, superlative most improper) Unsuitable to needs or circumstances; inappropriate; inapt. Not in keeping with conventional mores or good manners; …