Eel

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Old English ǣl, of Germanic origin; related to Dutch aal and German Aal .

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From Middle English ele, from Old English ǣl(“eel”), from Proto-West Germanic *āl, from Proto-Germanic *ēlaz(“eel”), which is of unknown origin.

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eel (n.)

Old English æl "eel," from Proto-Germanic *ælaz (source also of Old Frisian -el, Middle Dutch ael, Dutch aal, Old Saxon and Old High German al, German Aal, Old Norse all), which is of unknown origin, with no certain cognates outside Germanic. Used figuratively for slipperiness from at least 1520s.