knee breeches vs knickerbockers

knee breeches and knickerbockers both are nouns.

Word	Noun	Adjective	Verb	Adverb
knee breeches	Yes	No	No	No
knickerbockers	Yes	No	No	No

As nouns, knee breeches and knickerbockers are synonyms defined as:

knee breeches and knickerbockers: (used in the plural) trousers ending above the knee

Other synonyms of knee breeches include breeches, knee pants, knickers.

knee breeches (noun)	knickerbockers (noun)
(used in the plural) trousers ending above the knee	(used in the plural) trousers ending above the knee