The Collaborative International Dictionary
For aye
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.
For his mercies aye endure.
--Milton.
For aye, always; forever; eternally.