knuckle duster vs knuckles

knuckle duster and knuckles both are nouns.

Word	Noun	Adjective	Verb	Adverb
knuckle duster	Yes	No	No	No
knuckles	Yes	No	No	No

As nouns, knuckle duster and knuckles are synonyms defined as:

knuckle duster and knuckles: (used in the plural) a small metal weapon; worn over the knuckles on the back of the hand

Other synonyms of knuckle duster include brass knuckles, brass knucks, knucks.

knuckle duster (noun)	knuckles (noun)
(used in the plural) a small metal weapon; worn over the knuckles on the back of the hand	(used in the plural) a small metal weapon; worn over the knuckles on the back of the hand