The Etymology of Bridle
Bridle is a quietly ancient word — Old English brīdel, Proto-Germanic *bridilaz — built as an instrument-noun (a thing-for-doing) from a verbal root meaning to draw, twist, or weave, related to braid. The bridle is, etymologically, the twisted thing, which fits its braided leather construction. The verb to bridle (to control, restrain) emerged in the 14th century by metaphorical extension from the noun. The further sense of to bridle as in to bridle at a remark — to react with sudden indignation, head jerked back — comes from the 18th-century image of a horse pulling sharply on the bridle when startled. Bridle path (a track for bridled horses) is from the 1620s. The French verb brider (to bridle, to restrain) is itself a Frankish loan from Germanic, going back to the same source — meaning the word reached French not from Latin but from the Germanic ancestor English shares.