Union jack :  (noun)

1: national flag of the United Kingdom [syn: Union Jack, Union flag]

Dannebrog, Jolly Roger, Old Glory, Star-Spangled Banner, Stars and Stripes, Union Flag, and blue, banderole, banner, banneret, black flag, blue ensign, bunting, burgee, coachwhip, colors, ensign, flag, gonfalon, gonfanon, guidon, house flag, jack, long pennant, merchant flag, national flag, oriflamme, pennant, pennon, pennoncel, red, red ensign, royal standard, signal flag, standard, streamer, swallowtail, tricolor, vexillum, white,