obol (n.)

ancient Greek small coin and weight, 1660s, from Latin obolus, from Greek obolos, the name of a coin (sixth part of a drachme); identical with obelos "a spit, needle, broach; bar of metal used as a coin or weight" (see obelisk). So called from the original shape. Middle English had obolus as the name of a small measure of weight, also ob "halfpenny," from Latin ob., abbreviation of obolus.