[adjective] not suitable or right or appropriate; "slightly improper to dine alone with a married man"; "improper medication"
[adjective] not conforming to legality, moral law, or social convention; "an unconventional marriage"; "improper banking practices" Synonyms:unconventional, unlawful
[adjective] not appropriate for a purpose or occasion; "unsuitable attire for the office"; "said all the wrong things" Synonyms:unsuitable, wrong