concurrent (adj.)

early 15c., "collide, clash in hostility," from Latin concurrere "to run together, assemble hurriedly; clash, fight," in transferred use, "to happen at the same time," from assimilated form of com "together" (see con-) + currere "to run" (from PIE root *kers- "to run"). Sense of "to coincide, happen at the same time" is 1590s; that of "to agree in opinion" is 1580s in English.

Proto-Indo-European root meaning "to run."

It forms all or part of: car; career; cargo; caricature; cark; carpenter; carriage; carrier; carry; charabanc; charette; charge; chariot; concourse; concur; concurrent; corral; corridor; corsair; courant; courier; course; currency; current; curriculum; cursive; cursor; cursory; discharge; discourse; encharge; excursion; hussar; incur; intercourse; kraal; miscarry; occur; precursor; recourse; recur; succor.

It is the hypothetical source of/evidence for its existence is provided by: Greek -khouros "running;" Latin currere "to run, move quickly;" Lithuanian karšiu, karšti "go quickly;"Old Irish and Middle Welsh carr "cart, wagon," Breton karr "chariot," Welsh carrog "torrent;" Old Norse horskr "swift."