supple vs alter

supple is an adjective but alter is not an adjective.

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

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

Other hypernyms of supple include change, modify.

supple (adjective)	alter (adjective)
(used of e.g. personality traits) readily adaptable
gracefully thin and bending and moving with ease
(used of persons' bodies) capable of moving or bending freely

supple (verb)	alter (verb)
make pliant and flexible	remove the ovaries of
	become different in some particular way, without permanently losing one's or its former characteristics or essence
	cause to change; make different; cause a transformation
	insert words into texts, often falsifying it thereby
	make an alteration to