legitimate vs legalise

legitimate is an adjective but legalise is not an adjective.

Word	Noun	Adjective	Verb	Adverb
legitimate	No	Yes	Yes	No
legalise	No	No	Yes	No

As verbs, legitimate and legalise are synonyms defined as:

legitimate (adjective)	legalise (adjective)
of marriages and offspring; recognized as lawful
in accordance with recognized or accepted standards or principles
authorized, sanctioned by, or in accordance with law
based on known statements or events or conditions

legitimate (verb)	legalise (verb)
make (an illegitimate child) legitimate; declare the legitimacy of (someone)	make legal
show or affirm to be just and legitimate
make legal