knickers vs knickerbockers

knickers and knickerbockers both are nouns.

Word	Noun	Adjective	Verb	Adverb
knickers	Yes	No	No	No
knickerbockers	Yes	No	No	No

As nouns, knickers and knickerbockers are synonyms defined as:

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

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

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