a small flag or streamer, as that carried by cavalry, which is broad at one end and nearly pointed at the other, or that used to direct the movements of a body of infantry, or to make signals at sea; also, the flag of a guild or fraternity. in the united states service, each company of cavalry has a guidon.-one who carries a flag.-one of a community established at rome, by charlemagne, to guide pilgrims to the holy land.