per (prep.) Look up per at Dictionary.com
1580s (earlier in various Latin and French phrases), from Latin per "through, during, by means of, on account of, as in," from PIE root *per- (1) "Base of prepositions and preverbs with the basic meanings of 'forward,' 'through,' and a wide range of extended senses such as 'in front of,' 'before,' 'early,' 'first,' 'chief,' 'toward,' 'against,' 'near,' 'at,' 'around'" [Watkins]. Cognates: Sanskrit pari- "around, about, through," pura "before, formerly;" Avestan pairi- "around," paro "before;" Old Persian pariy; Hittite para- "on, forth;" Greek peri "around, about, near, beyond," paros "before," para "from beside, beyond," pro "before;" Latin pro "before, for, on behalf of, instead of," porro "forward," prae "before;" Old English fore (prep.) "before, in front of;" (adv.) "before, previously;" German vor "for;" Old Church Slavonic pra-dedu "great-grandfather;" Russian pere- "through;" Lithuanian per "through;" Old Irish air- Gothic fair-, German ver-, Old English fer-, intensive prefixes.