improper vs unlawful

improper and unlawful both are adjectives.

Word	Noun	Adjective	Verb	Adverb
improper	No	Yes	No	No
unlawful	No	Yes	No	No

As adjectives, improper and unlawful are synonyms defined as:

improper and unlawful: not conforming to legality, moral law, or social convention

Other synonyms of improper include unconventional.

improper (adjective)	unlawful (adjective)
not suitable or right or appropriate	contrary to or prohibited by or defiant of law
not appropriate for a purpose or occasion	contrary to or forbidden by law
not conforming to legality, moral law, or social convention	having no legally established claim
	not morally right or permissible
	not conforming to legality, moral law, or social convention