"Spanish coin," 1550s, from Spanish peso, literally "a weight," from Latin pensum, properly past participle of pendere "to hang, to cause to hang" (see pendant).
the monetary unit of several Latin American countries and the Philippines; it is divided into 100 centavos. The peso was introduced into Spain by the monarchs Ferdinand and Isabella, who reformed the Spanish coinage system in 1497; it did not come into common use, though, until the time of Charles I (the emperor Charles V)