Nadi (yoga)
Nāḍi (literally "river", here in the sense "tube, pipe") are the channels through which, in traditional Indian medicine and spiritual science, the energies of the subtle body are said to flow. They connect at special points of intensity called chakras.
Read more about Nadi (yoga): Early Reference, Functions and Activities, Ida, Pingala and Sushumna, Western Tradition and Interpretations