tetart-, tetarto- +

1. Defective vision or blindness in one fourth of the visual field.
2. A rare type of dichromatic vision (defective color vision in which one of the three cone pigments is missing) of doubtful existence, characterized by perception of red and green only, with blue and yellow perceived as an achromatic (gray) band.

Affected by tetartanopia; that is, having faulty blue-yellow discrimination.

Referring to a crystal having one fourth the planes, or faces, required by the maximum symmetry of the system to which it belongs.

A solid figure with four equilateral triangles; such as, its faces, six edges, and four vertices (highest points).