improper

UK: /ˌɪmˈprɒpə^r/ US: /ɪmˈprɑpɚ/ ,(im prop′ər)

WordReference Random House Learner's Dictionary of American English © 2025

im•prop•er /ɪmˈprɑpɚ/   adj. 

1. not belonging or applicable:
   drew some improper conclusions.
2. not agreeing with what is proper:
   improper conduct.
   [ it + be + ~ (+ for + obj) + to + verb]:
   It was improper (for you) to make that offer.
3. abnormal;
   irregular:
   signs of improper functioning.
4. not correct:
   improper laboratory procedures.

im•prop•er•ly, adv. See -propr-.

WordReference Random House Unabridged Dictionary of American English © 2025

im•prop•er  (im prop′ər), adj. 

1. not proper;
   not strictly belonging, applicable, correct, etc.;
   erroneous:
   He drew improper conclusions from the scant evidence.
2. not in accordance with propriety of behavior, manners, etc.:
   improper conduct at a funeral.
3. unsuitable or inappropriate, as for the purpose or occasion:
   improper attire for a formal dance.
4. abnormal or irregular:
   improper functioning of the speech mechanism.

• Latin improprius. See im-², proper
• 1535–45

im•prop′er•ly, adv. 
im•prop′er•ness, n. 
Synonyms

• 1. –3. inapplicable, unsuited, unfit.
• 2. indecorous.
  Improper, indecent, unbecoming, unseemly are applied to that which is unfitting or not in accordance with propriety.
  Improper has a wide range, being applied to whatever is not suitable or fitting, and often specifically to what does not conform to the standards of conventional morality:
  improper diet; improper behavior in church; improper language.
  Indecent, a strong word, is applied to what is offensively contrary to standards of propriety and esp. of modesty:
  indecent behavior, literature.
  Unbecoming is applied to what is esp. unfitting in the person concerned:
  conduct unbecoming a minister.
  Unseemly is applied to whatever is unfitting or improper under the circumstances:
  unseemly mirth.

Antonyms

• 1, 3. fitting, suitable.
• 2. proper.

Collins Concise English Dictionary © HarperCollins Publishers::

improper / ɪmˈprɒpə/ adjective

1. lacking propriety; not seemly or fitting
2. unsuitable for a certain use or occasion; inappropriate: an improper use for a tool
3. irregular or abnormal

imˈproperly adverb

imˈproperness noun