c.1300, “foot soldier;” late 14c., “one who goes on foot;” as a personal attendant, originally one who ran before or alongside his master’s carriage, announcing its arrival (and keeping it from tipping over). The modern, non-jogging servant sense is from c.1700, though the running footmen still were in service mid-18c. From foot + man.
1529, "footman, running footman, valet," from M.Fr. laquais "foot soldier, footman, servant" (15c.), probably from O.Prov. lacai, from lecai "glutton, covetous," from lecar "to lick." Alternative etymology is via Fr. from Catalan alacay, from Arabic al-qadi "the judge." Yet another guess traces it through Sp. lacayo, from It. lacchè, from Mod.Gk. oulakes, from Turk. ulak "runner, courier." This suits the original sense better, but OED says It. lacchè is from French. Sense of "servile follower" appeared 1588. As a political term of abuse it dates from 1939 in communist jargon.
1782, Scottish dial., "footman, liveried servant," of uncertain origin, perhaps a dim. variant of flanker. Sense of "flatterer, toady" first recorded 1855.