Английский Этимологический словарь - rack (3)

- "clouds driven before the wind," in M.E. also "rush of wind, collision, crash," possibly from O.E. racu "cloud," reinforced by O.N. rek "wreckage, jetsam," or by influence of O.E. wrжc "something driven." Often confused with wrack, especially in phrase rack and ruin, The distinction is that rack is "driven clouds;" wrack is "seaweed cast up on shore."