a. Cryst. [mod. f. Gr. ἀν priv. + ὀρθ-ός straight, right + -IC.] Irregular in crystallization; applied to all crystals which do not fall under one of the more regular systems; called also doubly oblique, triclinic, tetartoprismatic.
1864. Reader, 438/2. That the crystals included in the oblique and anorthic systems are formed by the combination of hemihedral and tetartohedral forms of the prismatic system.
1869. Phillips, Vesuv., x. 276. The sixth system, called anorthic, or doubly oblique, has its three axes unequal, and neither of them perpendicular to another.
