coupler vs clevis

coupler and clevis both are nouns.

Word	Noun	Adjective	Verb	Adverb
coupler	Yes	No	No	No
clevis	Yes	No	No	No

As nouns, clevis is a hyponym of coupler; that is, clevis is a word with a more specific, narrower meaning than coupler:

coupler: a mechanical device that serves to connect the ends of adjacent objects
clevis: a coupler shaped like the letter U with holes through each end so a bolt or pin can pass through the holes to complete the coupling; used to attach a drawbar to a plow or wagon or trailer etc.

Other hyponyms of coupler include clutch, fluid drive, swivel, turnbuckle, universal, universal joint.

coupler (noun)	clevis (noun)
a mechanical device that serves to connect the ends of adjacent objects	a coupler shaped like the letter U with holes through each end so a bolt or pin can pass through the holes to complete the coupling; used to attach a drawbar to a plow or wagon or trailer etc.