c. 1600, "provide food for," from Middle English catour (n.) "buyer of provisions" (c. 1400; late 13c. as a surname), a shortening of Anglo-French achatour "buyer" (Old North French acatour, Old French achatour, 13c., Modern French acheteur), from Old French achater "to buy," originally "to buy provisions," perhaps from Vulgar Latin *accaptare, from Latin ad- "to" (see ad-) + captare "to take, hold," frequentative of capere "to take," from PIE root *kap- "to grasp."
Or else from Vulgar Latin *accapitare "to add to one's capital," with second element from verbal stem of Latin caput (genitive capitis); see capital (adj.). Figuratively, "act as a purveyor," from 1650s. Related: Catered; catering.