'Fortissimo' definitions:

Definition of 'fortissimo'

From: WordNet
adverb
A direction in music; to be played very loudly [syn: fortissimo, very loudly] [ant: pianissimo, very softly]
adjective
Chiefly a direction or description in music
noun
(music) loud [syn: forte, fortissimo]

Definition of 'Fortissimo'

From: GCIDE
  • Fortissimo \For*tis"si*mo\ (? or ?), adv. [It., superl. of forte, adv. See Forte, adv.] (Mus.) Very loud; with the utmost strength or loudness. [1913 Webster]

Synonyms of 'fortissimo'

From: Moby Thesaurus