flag (n.) at English => English (English Etymology) Of Explained:

"cloth ensign," c.1480, now in all modern Gmc. languages, but apparently first recorded in Eng., origin unknown, but likely connected with flag (v.) or else, like it, onomatopoeic. A less likely guess is that it is from the flag in flagstone (q.v.) on notion of being square and flat. Flagship is 1672, ship bearing an admiral's flag. U.S. Flag Day (1894) is in reference to the adopting of the Stars and Stripes by the Continental Congress on June 14, 1777. ///

Related words:

flag  flag (v.)  Flag broom  Flag captain  flag captains  flag carrier  flag carriers  flag complex  Flag Day  flag days  flag down  flag fane  flag feather  flag football  flag gun  Flag leutenant  flag of convenience  FLAG OF THE UNITED STATES  Flag of truce  Flag of truse  Flag officer  flag officers  flag pole  flag poles  flag rank  flag ranks  Flag root  Flag share  flag smut  flag smut fungus  Flag station  flag stop  flag stops  flag up  flag waving  Flag {n}  flag, motherhood and apple pie  flag, motherhood, and apple pie  flag-bearer  flag-burning  flag-o  flag-waver  flag-waving  flaga  flagada  flagadas  flagar  flagbearer  flagbearers  flage  flagede  flagel  flagela  flagelaba  flagelabais  flagelábamos  flagelaban  flagelabas  flagelad  flagelado