"clouds driven before the wind," c.1300, 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.
wræc "something driven." Originally a northern word, perhaps from an unrecorded Scand. cognate of O.E.
racu. Often confused with
wrack (q.v.), especially in phrase
rack and ruin (1599). The distinction is that
rack is "driven clouds;"
wrack is "seaweed cast up on shore."
[rak] 
