Noun
double bridle (plural double bridles)
(equestrianism) A Weymouth bridle, which uses both a bradoon, held by a sliphead, and a curb bit, and is used with two reins.
At the upper levels a plain cavesson is used on a double bridle. Source: Internet
If a double bridle is used, a plain cavesson or crank noseband must be worn. Source: Internet