Emily Dickinson Lexicon

O'CEAN, n. [o'shun; L. oceanus; Gr. ωκεανος; Fr. ocean; Ir. ocein, aigein; W. eigiawn, aig or eigion. In Welsh, the word is rendered a great source, the middle, the abyss or great deep, and is allied in orthography to eigian, force, or a forcing out, a producing; eigiaw, to bring forth, from aig, what brings forth, the female, the womb, the sea, a shoal of fishes, a flock, or herd. Bochart cites many authorities to prove that the ancients understood the ocean to encompass the earth, and he supposes it to be derived from the Heb. Ch. and Syr. חוג hog, to encompass, whence a circle. This is probably an error. The word seems to have for its origin greatness or extent.]

1. The vast body of water which covers more than three fifths of the surface of the globe, called also the sea, or great sea. It is customary to speak of the ocean as if divided into three parts, the Atlantic ocean, the Pacific ocean, and the Indian ocean; but the ocean is one mass or body, partially separated by the continents of Europe, Asia and Africa on one side, and by America on the other.
2. An immense expanse; as, the boundless ocean of eternity; oceans of duration and space. Locke.