But this hopeful breakthrough turned out to be no more than a deviously effective pretext for his escape.
1590s, "out of the way," from Latin devius "out of the way, remote, off the main road," from de via (see deviate). Originally in the Latin literal sense; figurative sense of "deceitful" is first recorded 1630s. Related: Deviously; deviousness. Figurative senses of the Latin word were "retired, sequestered, wandering in the byways, foolish, inconsistent."