XIII vs baker's dozen

XIII and baker's dozen both are nouns.

Word	Noun	Adjective	Verb	Adverb
XIII	Yes	No	No	No
baker's dozen	Yes	No	No	No

As nouns, XIII and baker's dozen are synonyms defined as:

XIII and baker's dozen: the cardinal number that is the sum of twelve and one

Other synonyms of XIII include 13, long dozen, thirteen.

XIII (noun)	baker's dozen (noun)
the cardinal number that is the sum of twelve and one	the cardinal number that is the sum of twelve and one