The Collaborative International Dictionary of English v.0.48:

Aye \Aye\, Ay \Ay\, adv. [Icel. ei, ey; akin to AS. [=a],
   [=a]wa, always, Goth. aiws an age, Icel. [ae]fi, OHG, ?wa, L.
   aevum, Gr. ? an age, ?, ?, ever, always, G. je, Skr. ?va
   course. ?, ?. Cf. Age, v., Either, a., Or, conj.]
   Always; ever; continually; for an indefinite time.
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         For his mercies aye endure.              --Milton.
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   For aye, always; forever; eternally.
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