peso (n.)

"Spanish coin, the Spanish dollar," also a coin in various Spanish-American nations,  1550s, from Spanish peso, literally "a weight," from Medieval Latin pensum, properly past participle of Latin pendere "to hang, cause to hang; weigh; pay" (from PIE root *(s)pen- "to draw, stretch, spin"). For the financial sense of the Latin verb, see pound (n.1).