Mudra
मुद्रा
mudrā
Mudra literally meant, seal or imprint or gesture
It is customary to make some fixed symbolic postures with hands and body to express some message or feeling. Mudra is meant by these gestures. Hands joining to wish is Namaskar is a Mudra; it is a traditional way of greeting. Dancers use mudra to tell story and express various complex feelings.
Yoga and Tantra go further and use mudras to activate spiritual powers. Chin mudra is one such; it is recommended while meditating.