late 14c., "magistrate in ancient Rome," from Old French consule and directly from Latin consul "magistrate in ancient Rome," probably originally "one who consults the Senate," from consulere "to deliberate, take counsel" (see consultation).
Modern sense began with use as appellation of various foreign officials and magistrates, "a representative chosen by a community of merchants living in a foreign country; an agent appointed by a government or ruler to represent the interests of its subjects and traders in a foreign place" (c.1600), an extended sense that developed 13c. in the Spanish form of the word.