rankle vs vex

rankle and vex both are verbs.

Word	Noun	Adjective	Verb	Adverb
rankle	No	No	Yes	No
vex	No	No	Yes	No

As verbs, vex is a hypernym of rankle; that is, vex is a word with a broader meaning than rankle:

Other hypernyms of rankle include annoy, bother, chafe, devil, get at, get to, gravel, irritate, nark, nettle, rag, rile.

rankle (verb)	vex (verb)
gnaw into; make resentful or angry	be a mystery or bewildering to
	subject to prolonged examination, discussion, or deliberation
	change the arrangement or position of
	cause annoyance in; disturb, especially by minor irritations
	disturb the peace of mind of; afflict with mental agitation or distress