fortissimo vs loud

fortissimo is a noun but loud is not a noun.

Word	Noun	Adjective	Verb	Adverb
fortissimo	Yes	Yes	No	Yes
loud	No	Yes	No	Yes

fortissimo (noun)	loud (noun)
a musical composition or musical passage to be performed very loudly

fortissimo (adjective)	loud (adjective)
(chiefly a direction or description in music) very loud and strong	characterized by or producing sound of great volume or intensity
	(used chiefly as a direction or description in music) indicating that said piece or segment should be played loudly
	tastelessly showy

fortissimo (adverb)	loud (adverb)
a direction in music; to be played very loudly	with relatively high volume