mid-15c., Scottish ydy, possibly related to Old Norse iða "whirlpool," from Proto-Germanic *ith- "a second time, again," which is related to the common Old English prefix ed- "again, backwards; repetition, turning" (forming such words as edðingung "reconciliation," edgift "restitution," edniwian "to renew, restore," edhwierfan "to retrace one's steps," edgeong "to become young again"). Compare Old English edwielle "eddy, vortex, whirlpool." The prefix is from PIE root *eti "above, beyond" (Cognates: Latin et, Old High German et-, Gothic iþ "and, but, however"). Related: Eddies.

1730 (transitive); 1810 (intrans.), from eddy, n.. Related: Eddied; eddying.