per-

PIE preposition meaning forward, through, or far.‍​‌​‍​‍​‌​‍​‌​‌​‌​‍​‍​‍​‌​‍​‌​‌​‍​‌​‌​‍​‍​‍​‌​‍​‍​‍​‍​‌​‍​‍​‍​‍ One of the most common PIE prefixes, yielding Latin pro/per, English "for/fore," Greek pro.

Discussion

*per- is a Proto-Indo-European preposition and preverb meaning "forward," "through," or "far," arguably the most productive spatial morpheme in the entire proto-language.‍​‌​‍​‍​‌​‍​‌​‌​‌​‍​‍​‍​‌​‍​‌​‌​‍​‌​‌​‍​‍​‍​‌​‍​‍​‍​‍​‌​‍​‍​‍​‍

Latin per "through" and pro "forward, for" yield massive English vocabulary: per-, pro-, pre- (from prae), perfect, perform, permit, persist, provide, produce, progress, and hundreds more. Greek perí "around" (whence peri- in perimeter, period, peripheral) and pró "before" (whence problem, program, prophet) extend the family.

Sanskrit pári "around" and prá "forward" confirm the Indo-Iranian branch. In Germanic, Old English for/fore "before, for" (modern English for, fore, before, first, far, further) reflect the root with Grimm's Law (*p > f). German für "for," vor "before," and ver- (prefix) continue the pattern.

Old Irish ar "before" and Welsh er/ar show Celtic attestation. Lithuanian per "through" and pra- "past" confirm Balto-Slavic.

The root's extraordinary productivity stems from its basic spatial meaning being extendable to temporal (before), purposive (for), and completive (through/thoroughly) senses. Modern descendants number in the hundreds across English alone.

Notes

Source of Latin "per", English "far", "for". Traversal and distance marker.