Definition - What does Vibhuti mean?
Vibhuti is a Sanskrit word that refers to a sacred ash used in Hindu rituals. It is made from the white ash of wood burnt in the homa (sacred fire). This ash is used to draw three lines on the forehead of the devotee, in order to show devotion to the god, Shiva.
The three lines of vibhuti smeared across the forehead are called tripundra, representing the threefold power of Shiva: power of will, power of knowledge and power of action.
Yogapedia explains Vibhuti
The sacred vibhuti ash reminds the devotee to avoid egotistical and worldly longings. It is sometimes worn with a red dot on the forehead as a reminder that the universe is formed by Shiva and shakti.
Wearing vibhuti is mandatory for the devotees of Shiva. It is also sometimes worn on the chest, arms and stomach. It is believed that great yogis, saints and gurus should wear tripundra made from vibhuti at all times.
Vibhuti may also be made from cow dung, called gomaya, cremation ashes or rice husks.