Emily Dickinson Lexicon

AY, or AYE, adv. [G. D. Dan. Sw. ja, pron. ya; Dan. eja; Corn. ia; Ar. ya; Fr. oui. It may be a contracted word.]

Yes, yea, a word expressing assent, or an affirmative answer to a question. It is used also to enforce the sense of what is asserted, equivalent to even so, truly, certainly.