WordWeb Online

1. Not suitable or right or appropriate
   "slightly improper to dine alone with a married man"; "improper medication"; "improper attire for the golf course"
    
2. Not conforming to legality, moral law, or social convention
   "improper banking practices"
   - unconventional, unlawful
    
3. Not appropriate for a purpose or occasion
   - wrong

See also: correctitude, improperly, improperness, inappropriate, incorrect, indecent, indecorous, indelicate, irregular, out-of-the-way, properness, propriety, unbecoming, uncomely, unfit, unseemly, untoward, wrong

Antonym: proper

Encyclopedia: Improper