sorrowful vs mourning

sorrowful is not a noun while mourning is a noun.

Word	Noun	Adjective	Verb	Adverb
sorrowful	No	Yes	No	No
mourning	Yes	Yes	No	No

sorrowful (noun)	mourning (noun)
	the passionate and demonstrative activity of expressing grief
	state of sorrow over the death or departure of a loved one

sorrowful (adjective)	mourning (adjective)
experiencing or marked by or expressing sorrow especially that associated with irreparable loss	sorrowful through loss or deprivation