word-forming element meaning "above, over, beyond," from Latin super (adverb and preposition) "above, over, on the top (of), beyond, besides, in addition to," from *(s)uper-, variant form of PIE root *uper "over." In English words from Old French, it appears as sur-. The primary sense seems to have shifted over time from usually meaning "beyond" to usually meaning "very much," which can be contradictory. E.g. supersexual, which is attested from 1895 as "transcending sexuality," from 1968 as "very sexual."
highway n.
Old English heahweg "main road from one town to another;" see high (adj.) in sense of "main" + way (n.).
High street (Old English heahstræte) was the word before 17c. applied to highways and main roads, whether in the country or town, especially one of the Roman roads. In more recent usage, it generally is the proper name of the street of a town which is built upon a highway and was the principal street of the place.
Highway robbery, robbery committed near a highway, is from 1707, formerly the only sort punishable in common law by death; as a trivial expression for something too costly, by 1886.