Derived from "buddhadatu or buddhadhatu" (Sanskrit), which means "essence of the Buddha," from बुद्ध buddha, "conscious, awakened" and धातु dhatu, "element, primary element, cause, mineral".
The term buddhadhatu appeared in Mahayana scripture as a reference to tathagatagarbha, the "embryo of the Buddha," also called Buddha Nature. In general use, this describes that element in us that has the potential to become a Buddha, an "awakened one."