"improper" in the adjective sense
1. improper
not suitable or right or appropriate
"slightly improper to dine alone with a married man"
"improper medication"
"improper attire for the golf course"
2. improper, unconventional, unlawful
not conforming to legality, moral law, or social convention
"an unconventional marriage"
"improper banking practices"
3. improper, wrong
not appropriate for a purpose or occasion
"said all the wrong things"
Source: WordNet® (An amazing lexical database of English)
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