Origin and history of *kers-

c. 1300, "wheeled vehicle," from Anglo-French carre, Old North French carre, from Vulgar Latin *carra, related to Latin carrum, carrus (plural carra), originally "two-wheeled Celtic war chariot," from Gaulish karros, a Celtic word (compare Old Irish and Welsh carr "cart, wagon," Breton karr "chariot"), from PIE *krsos, from root *kers- "to run." The Celtic-Latin word also made it into Greek, as karron "wagon with four wheels."

"From 16th to 19th c. chiefly poetic, with associations of dignity, solemnity, or splendour ..." [OED]. Used in U.S. by 1826 of railway freight carriages and of passenger coaches on a railway by 1830; by 1862 of streetcars or tramway cars. The extension to "automobile" is by 1896, but between 1831 to the first decade of 20c. the cars meant "railroad train." Car bomb is attested from 1972, in a Northern Ireland context. The Latin word also is the source of Italian and Spanish carro, French char.

1530s, "a running (usually at full speed), a course" (especially of the sun, etc., across the sky), from French carriere "road, racecourse" (16c.), from Old Provençal or Italian carriera, from Vulgar Latin *(via) cararia "carriage (road), track for wheeled vehicles," from Latin carrus "chariot" (see car). The sense of "general course of action or movement" is from 1590s, hence "course of one's public or professional life" (1803).