prediluvian adjective 1noun 1forms 1 adjective1 •Before the Flood; antediluvian. noun1 •One who lived before the Flood; an antediluvian.When Noah in ark, with his sons did embark, / Prediluvians, uplifted and pompous, / Deem’d his nautical scheme a fantastical dream, / And pronounc’d the projector non compos. — 1786 formsprediluvians