"character of being musical," 1812, from musical (adj.) + -ity.
Entries linking to musicality
musical adj.
early 15c., "pertaining to music;" mid-15c., "tuneful, harmonious;" late 15c., "adept at making music," from Medieval Latin musicalis, from Latin musica (see music). Related: Musically. Musical box is from 1829. Children's or parlor game musical chairsis attested from 1862, hence use of musical as a modifier meaning "changing rapidly from one to another possessor" (1924).
Instrumental and vocal music, the quadrille and country-dance, occupy a portion of the time. No waltzing is however permitted. After dancing, round games follow, as Terza, "The Post," Musical Chairs, Cross Questions, all tending to amuse and promote exercise, until the partial extinguishing of the gas, at ten p.m., gives warning of approaching bedtime. [The Rev. R. Wodrow Thomson, "Ben Rhydding, the Asclepia of England," 1862]
In mid-19c. makers of musical boxes also advertised musical chairs, "playing beautiful tunes simply by the weight of the person sitting in them."
-ity
word-forming element making abstract nouns from adjectives and meaning "condition or quality of being ______," from Middle English -ite, from Old French -ete (Modern French -ité) and directly from Latin -itatem (nominative -itas), suffix denoting state or condition, composed of -i- (from the stem or else a connective) + the common abstract suffix -tas (see -ty (2)).
Roughly, the word in -ity usually means the quality of being what the adjective describes, or concretely an instance of the quality, or collectively all the instances; & the word in -ism means the disposition, or collectively all those who feel it. [Fowler]