dead soul vs decedent

dead soul and decedent both are nouns.

Word	Noun	Adjective	Verb	Adverb
dead soul	Yes	No	No	No
decedent	Yes	No	No	No

As nouns, dead soul and decedent are synonyms defined as:

Other synonyms of dead soul include dead person, deceased, deceased person, departed.

dead soul (noun)	decedent (noun)
someone who is no longer alive	someone who is no longer alive