Anatase—also known as octahedrite—is one of the five mineral forms of titanium(IV) oxide or titanium dioxide (TiO2). The term anatase comes from the Greek ἀνά (ana, "stretched") and ἀνάτασις (anatasis, "elongation"), referring to the length of its pyramidal faces, which are longer in relation to their bases than those of other tetragonal minerals.