Part of speech: Adjective
not suitable or right or appropriate
Example: slightly improper to dine alone with a married man; improper medication; improper attire for the golf course
Part of speech: Adjective
not conforming to legality, moral law, or social convention
Example: an unconventional marriage; improper banking practices
Part of speech: Adjective
not appropriate for a purpose or occasion
Example: said all the wrong things
Unconventional, Unlawful, Improper, Wrong
The word "improper" comes from Latin improprius, which comes from Middle French impropre.
Medieval scholars created new Latin words for modern concepts, keeping the language alive for centuries.