depressing vs melancholy

depressing is not a noun while melancholy is a noun.

Word	Noun	Adjective	Verb	Adverb
depressing	No	Yes	No	No
melancholy	Yes	Yes	No	No

depressing (noun)	melancholy (noun)
	a humor that was once believed to be secreted by the kidneys or spleen and to cause sadness and melancholy
	a feeling of thoughtful sadness
	a constitutional tendency to be gloomy and depressed

depressing (adjective)	melancholy (adjective)
causing sad feelings of gloom and inadequacy	grave or even gloomy in character
	characterized by or causing or expressing sadness