knucks vs brass knucks

knucks and brass knucks both are nouns.

Word	Noun	Adjective	Verb	Adverb
knucks	Yes	No	No	No
brass knucks	Yes	No	No	No

As nouns, knucks and brass knucks are synonyms defined as:

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

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

knucks (noun)	brass knucks (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