I was thinking about posting this, but the AHD derives it from ovatus, past participle of ovare to rejoice.

Plutarch's Latin etymologies should be treated with caution. He says himself:

But for me, I live in a little town, where I am willing to continue, lest it should grow less; and having had no leisure, while I was in Rome and other parts of Italy, to exercise myself in the Roman language, on account of public business and of those who came to be instructed by me in philosophy, it was very late, and in the decline of my age, before I applied myself to the reading of Latin authors. Upon which that which happened to me, may seem strange, though it be true; for it was not so much by the knowledge of words, that I came to the understanding of things, as by my experience of things I was enabled to follow the meaning of words. But to appreciate the graceful and ready pronunciation of the Roman tongue, to understand the various figures and connection of words, and such other ornaments, in which the beauty of speaking consists, is, I doubt not, an admirable and delightful accomplishment; but it requires a degree of practice and study, which is not easy, and will better suit those who have more leisure, and time enough yet before them for the occupation.



Bingley

Bingley