The gauntlet, in medieval armor, is a glove, usually of leather covered with iron, which formed a part of the equipment of knights. They were introduced in the thirteenth century, and it was a custom to throw one of them down as a challenge. In heraldry, the gauntlet for the left hand was expressed by the word sinister, for the right, dexter. Since the left side was regarded as unlucky the term sinister now means inauspicious, dishonest or of ill report.
Gauntlet also refers to a kind of military punishment in which the prisoner, stripped to the waist, had to run between two files of soldiers armed with sticks or other instruments with which they struck him as he passed. Hence the term "running the gauntlet."
