資料來源 : Webster's Revised Unabridged Dictionary (1913)

Triquadrantal \Tri`quad*ran"tal\, a. [Pref. tri- + quadrantal.]
   (Spherical Trig.)
   Having three quadrants; thus, a triquadrantal triangle is one
   whose three sides are quadrants, and whose three angles are
   consequently right angles.