prehension n.

word-forming element meaning "before," from Old French pre- and Medieval Latin pre-, both from Latin prae (adverb and preposition) "before in time or place," from PIE *peri- (source also of Oscan prai, Umbrian pre, Sanskrit pare "thereupon," Greek parai "at," Gaulish are- "at, before," Lithuanian prie "at," Old Church Slavonic pri "at," Gothic faura, Old English fore "before"), extended form of root *per- (1) "forward," hence "beyond, in front of, before."

The Latin word was active in forming verbs. Also see prae-. Sometimes in Middle English muddled with words in pro- or per-.

also *ghed-, Proto-Indo-European root meaning "to seize, to take." 

It forms all or part of: apprehend; apprentice; apprise; beget; comprehend; comprehension; comprehensive; comprise; depredate; depredation; emprise; enterprise; entrepreneur; forget; get; guess; impresario; misprision; osprey; predatory; pregnable; prehensile; prehension; prey; prison; prize (n.2) "something taken by force;" pry (v.2) "raise by force;" reprehend; reprieve; reprisal; reprise; spree; surprise.

It is the hypothetical source of/evidence for its existence is provided by: Greek khandanein "to hold, contain;" Lithuanian godėtis "be eager;" second element in Latin prehendere "to grasp, seize;" Welsh gannu "to hold, contain;" Russian za-gadka "riddle;" Old Norse geta "to obtain, reach; to be able to; to beget; to learn; to be pleased with;" Albanian gjen "to find."

late Old English, prisoun, "place of confinement or involuntary restraint, dungeon, jail," from Old French prisoun "captivity, imprisonment; prison; prisoner, captive" (11c., Modern French prison), altered (by influence of pris "taken;" see prize (n.2)) from earlier preson, from Vulgar Latin *presionem, from Latin prensionem (nominative prensio), shortening of prehensionem (nominative *prehensio) "a taking," noun of action from past-participle stem of prehendere "to take" (from prae- "before," see pre-, + -hendere, from PIE root *ghend- "to seize, take").

In early use often "captivity, the condition of being in captivity or confinement;" hence, by extension, "a place for captives, a public building for confinement or safe custody of criminals and others committed by legal process," the main modern sense.