Webster's Revised Unabridged Dictionary · 1913

Crucial

Crucial (kr?"shal) , adjective

[French crucial, from Latin crux, crucis, cross, torture. See Cross.]

1.
Having the form of a cross; appertaining to a cross; cruciform; intersecting; as, crucial ligaments; a crucial incision.
2.
Severe; trying or searching, as if bringing to the cross; decisive; as, a crucial test.