n. 小辔头

[ noun ]
a bit resembling a snaffle bit; used with a separate curb
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Bridoon \Bri*doon"\, n. [F. bridon, from bride; of German
origin. See {Bridle}, n.] (Mil.)
The snaffle and rein of a military bridle, which acts
independently of the bit, at the pleasure of the rider. It is
used in connection with a curb bit, which has its own rein.
--Campbell.