[cru.cial] adj [F, fr. L cruc-, crux cross] (1706) 1 archaic: cruciform
2. a: important or essential as resolving a crisis: decisive "a ~ step" b: marked by final determination of a doubtful issue "the ~ game of a series" c: important, significant "what use we make of them will be the ~ question --Stanley Kubrick" syn see acute