Having threefold symmetry.

synonym: rhombohedral.

Roget 94: trifid; trisected etc. v.; tripartite, trichotomous^†, trisulcate^†.    Triadelphous^†, triangular, tricuspid, tricapsular^†, tridental^†, tridentate, tridentiferous^†, trifoliate, trifurcate, trigonal^†, trigrammic^†, trigrammatic^†, tripetalous^†, tripodal, tripodic^†, triquetral^†, triquetrous^†.    ... show more

Roget 244: angular, bent, crooked, aduncous^†, uncinated^†, aquiline, jagged, serrated; falciform^†, falcated^†; furcated^†, forked, bifurcate, zigzag; furcular^†; hooked; dovetailed; knock kneed, crinkled, akimbo, kimbo^†, geniculated^†; oblique etc. 217.    fusiform [Micro.], wedge-shaped, cuneiform; cuneate^†, multangular^†, oxygonal^†; triangular, trigonal^†, trilateral; quadrangular, quadrilateral; foursquare; rectangular, square, multilateral; polygonal etc. n.; cubical, rhomboid, rhomboidal, pyramidal.    ... show more