somersault n.

word-forming element meaning "above, over, beyond, before," from Latin supra "above, over, before, beyond, on the upper side," in supera (parte), literally "on the upper (side)," from old fem. ablative singular of superus (adj.) "above," related to super "above, over" (from PIE root *uper "over"). In English interchangeable with, but somewhat more technical than, super-. Rare as a prefix in Latin, more common in Medieval Latin, in English chiefly scientific or technical.

1560s, "leaping," a heraldic term, from Latin salientem (nominative saliens), present participle of salire "to leap," from a PIE root of uncertain form (source also of Sanskrit sisarsi, sisrate "to flow, run, hurry;"Greek hallesthai "to leap," Middle Irish saltraim "I trample," Middle Welsh sathar "trampling").

The meaning "pointing outward" (preserved in military usage) is from 1680s; that of "prominent, striking" first recorded 1840, from salient point (1670s), which refers to the heart of an embryo, which seems to leap, and translates Latin punctum saliens, going back to Aristotle's writings. Hence, the "starting point" of anything.

Proto-Indo-European root meaning "over."

It forms all or part of: hyper-; insuperable; over; over-; sirloin; somersault; soprano; soubrette; sovereign; sum; summit; super-; superable; superb; superior; supernal; supra-; supreme; sur-.

It is the hypothetical source of/evidence for its existence is provided by: Sanskrit upari, Avestan upairi "over, above, beyond;" Greek hyper, Latin super "above, over;" Old English ofer "over," German über, Gothic ufaro "over, across;" Gaulish ver-, Old Irish for.