Main Entry: cusp

Pronunciation: \ˈkəsp\

Function: noun

Etymology: Latin cuspis point

Date: 1585

: point, apex: as a : a point of transition (as from one historical period to the next) : turning point; also : edge, verge <on the cusp of stardom> b : either horn of a crescent moon c : a fixed point on a mathematical curve at which a point tracing the curve would exactly reverse its direction of motion d : an ornamental pointed projection formed by or arising from the intersection of two arcs or foils e (1) : a point on the grinding surface of a tooth (2) : a fold or flap of a cardiac valve

— cus·pate \ˈkəs-ˌpāt, -pət\ adjective

— cusped \ˈkəspt\ adjective

[cusp illustration]