JACOBUS, a gold coin, worth twenty-five shillings, and so called from King James I. of England, in whose reign it was struck. There are two kinds of Jacobus, the old and the new; the former valued at twenty-five shillings, weighing six pennyweights ten grains; the latter, called also Carolus, valued at twenty-three shillings, and in weight five pennyweights twenty grains.