"act of bending the knee," especially in worship, early 15c., from Middle French génuflexion (14c.) and directly from Medieval Latin genuflectionem (nominative genuflexio) "bending of the knee," noun of action from past participle stem of Late Latin genuflectere "genuflect," properly genu flectere "to bend the knee," from Latin genu "knee" (see knee (n.)) + flectere "to bend" (see flexible).