Emily Dickinson Lexicon

TRIG-ON-OM'E-TRY, n. [Gr. τριγωνος, a triangle, and μετρεω, to measure.]

The measuring of triangles; the science of determining the sides and angles of triangles, by ineans of certain parts which are given. When this science is applied to the solution of plane triangles, it is called plane trigonometry; when its application is to spherical triangles, it is called spherical trigonometry.