Genuflection (or genuflexion), bending at least one knee to the ground, was from early times a gesture of deep respect for a superior. In 328 BC, Alexander the Great introduced into his court etiquette some form of genuflection already in use in Persia. In the Byzantine Empire even senators were required to genuflect to the emperor.
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genuflection An act of reverence consisting of falling onto (usually) one knee.