late 15c., from superior (adj.) + -ity, or directly from Medieval Latin superioritatem (nominative superioritas), from superior.
Entries linking to superiority
superior adj.
late 14c., "higher in position," from Old French superior "higher, upper" (Modern French superieur), from Latin superiorem (nominative superior) "higher," comparative of superus "situated above, upper," from super "above, over" (from PIE root *uper "over").
Meaning "higher in rank or dignity" is attested from late 15c.; sense of "of a higher nature or character" is attested from 1530s. Original sense was preserved more strongly in French (as in les étages supérieur "the upper stories"), and in Lake Superior, a loan-translation of French Lac Supérieur, literally "upper lake" (at 600 feet above sea-level it has the highest surface elevation of the five Great Lakes and is the furthest north).
Surprise a person of the that is supposed to keep servants cleaning his own boots, & either he will go on with the job while he talks to you, as if it were the most natural thing in the world, or else he will explain that the bootboy or scullery-maid is ill & give you to understand that he is, despite appearances, superior to boot-cleaning. If he takes the second course, you conclude that he is not superior to it; if the first, that perhaps he is. [Fowler]
-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]