buckle vs fasten

buckle is a noun but fasten is not a noun.

Word	Noun	Adjective	Verb	Adverb
buckle	Yes	No	Yes	No
fasten	No	No	Yes	No

As verbs, fasten is a hypernym of buckle; that is, fasten is a word with a broader meaning than buckle:

Other hypernyms of buckle include fix, secure.

buckle (noun)	fasten (noun)
fastener that fastens together two ends of a belt or strap; often has loose prong
a shape distorted by twisting or folding

buckle (verb)	fasten (verb)
bend out of shape, as under pressure or from heat	make tight or tighter
fasten with a buckle or buckles	become fixed or fastened
fold or collapse	cause to be firmly attached
	attach to