资料来源 : pyDict

三角的,三角形的,断面呈三角的

资料来源 : Webster's Revised Unabridged Dictionary (1913)

Trigonal \Trig"o*nal\, a.
   Having three angles, or corners; triangular; as, a trigonal
   stem, one having tree prominent longitudinal angles.

资料来源 : WordNet®

trigonal
     adj : having three-fold symmetry [syn: {rhombohedral}]