solemnise vs alter

solemnise and alter both are verbs.

Word	Noun	Adjective	Verb	Adverb
solemnise	No	No	Yes	No
alter	No	No	Yes	No

As verbs, alter is a hypernym of solemnise; that is, alter is a word with a broader meaning than solemnise:

Other hypernyms of solemnise include change, modify.

solemnise (verb)	alter (verb)
make solemn and grave	remove the ovaries of
observe or perform with dignity or gravity	become different in some particular way, without permanently losing one's or its former characteristics or essence
perform (the wedding ceremony) with proper ceremonies	cause to change; make different; cause a transformation
	insert words into texts, often falsifying it thereby
	make an alteration to