knee breeches vs knickers

knee breeches and knickers both are nouns.

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

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

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

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

knee breeches (noun)	knickers (noun)
(used in the plural) trousers ending above the knee	(used in the plural) underpants worn by women
	(used in the plural) trousers ending above the knee