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 class 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]
early 15c., from Latin superior (see superior (adj.)), used in Medieval Latin with a noun sense of "one higher, a superior."