kechari mudra

(also spelled khechari mudra) literally, the "seal, or gesture, of moving in the void," being the more intense form of the "tongue lock." This energy seal requires months of gradually cutting the frenulum linguae, or lower tendon of the tongue, so that the tongue can actually extend back and up into the root of the nasal cavity. NOTE: Kechari mudra is NOT recommended for householders. Instead, the nabho mudra is recommended, as it only requires turning the tip of the tongue up and backwards as far as possible. The tongue's capacity to stretch gradually increases with regular practice. Kechari mudra is sometimes used either with, or instead of, jalandhara bandha (the "chin lock") to reverse the upwards moving prana vayu and send it back downwards to be heated and re-energized at Manipura. Also, in some texts, the term kechari mudra refers to a combination of the "tongue lock" and the "eye lock" (sambhavi mudra) performed together. For more information, see sambhavi mudra.