Main Entry: crux

Pronunciation: \ˈkrəks, ˈkru̇ks\

Function: noun

Inflected Form(s): plural crux·es also cru·ces \ˈkrü-ˌsēz\

Etymology: Latin cruc-, crux cross, torture

Date: 1718

1 : a puzzling or difficult problem : an unsolved question
2 : an essential point requiring resolution or resolving an outcome <the crux of the problem>
3 : a main or central feature (as of an argument)