fossilise vs mature

fossilise is not an adjective while mature is an adjective.

Word	Noun	Adjective	Verb	Adverb
fossilise	No	No	Yes	No
mature	No	Yes	Yes	No

As verbs, mature is a hypernym of fossilise; that is, mature is a word with a broader meaning than fossilise:

Other hypernyms of fossilise include age, get on, maturate, senesce.

fossilise (adjective)	mature (adjective)
	having reached full natural growth or development
	characteristic of maturity
	(of birds) having developed feathers or plumage; often used in combination
	fully developed or matured and ready to be eaten or used
	fully considered and perfected

fossilise (verb)	mature (verb)
convert to a fossil	cause to ripen and discharge pus
become mentally inflexible	develop and reach maturity; undergo maturation
	grow old or older
	become due for repayment
	cause to ripen or develop fully
	develop and work out fully in one's mind