corpus vs principal sum

corpus and principal sum both are nouns.

Word	Noun	Adjective	Verb	Adverb
corpus	Yes	No	No	No
principal sum	Yes	No	No	No

As nouns, corpus and principal sum are synonyms defined as:

corpus and principal sum: capital as contrasted with the income derived from it

Other synonyms of corpus include principal.

corpus (noun)	principal sum (noun)
the main part of an organ or other bodily structure	capital as contrasted with the income derived from it
a collection of writings
capital as contrasted with the income derived from it