1) Bowing 2) Genuflection 3) Obeisance 1) Genuflection 
Genuflexion is the act of bending the knees in worship.
genuflection, genuflexion 1. An act of bending the knee or touching it to the ground in reverence or worship. 2. An attitude; a gesture: involving, like prostration, a profession of dependence or helplessness, and therefore very naturally adopted for praying and for worship in general.