Yam is the seed syllable (bija mantra) of anahata, the heart chakra, in the tantric and hatha-yoga chakra system. As with the other centres, anahata is meditated upon through an element, a lotus of a fixed number of petals, and a seed sound; it is associated with the element air and with a twelve-petalled lotus, and Yam is the sound used to concentrate upon and, in the understanding of the tradition, to enliven it. Its name, anahata, means unstruck, evoking a subtle sound produced without any two things striking together, and the centre is linked in the tradition with love and compassion. Like the other bijas, Yam is treated as sound rather than as translatable speech, employed in inward recitation and visualisation, and its assignment to the airy heart-centre derives from the medieval tantric scheme codified in the yoga literature and standard across its common forms.
Yam is identified in the same tantric physiological scheme, the Shatchakra Nirupana as transmitted through Sir John Woodroffe's The Serpent Power (1919), as the bija, or seed syllable, of the Anahata chakra, the heart centre, traditionally visualised as a twelve-petalled lotus and associated with the air element and with love, compassion and equilibrium between the lower, bodily centres and the higher, more purely mental ones above it. The Anahata centre's name is itself sometimes glossed as the "unstruck" sound, a reference in some commentarial traditions to a subtle, self-arising resonance said to be perceptible in advanced meditative states without any external striking or vibration, distinguishing it philosophically from ordinary, physically produced sound.