[app. f. Du. trap step (cf. next) + BRILLIANT sb.] In diamond-cutting, a form of brilliant in which each of the foundation squares is divided horizontally into two triangular facets at an obtuse angle (when viewed in elevation); also called step-brilliant, split-brilliant.
1877. Knight, Dict. Mech., s.v. Gem-cutting, There are several varieties of brilliant cuts, known as—Half-brilliant … Full brilliant … Split or trap-brilliant … Double brilliant or Lisbon cut.
1891. in Cent. Dict.
