Emily Dickinson Lexicon

BOS'PO-RUS, n. [Gr. βους, an ox, and πορος, a passage.]

A narrow sea or a strait, between two seas or between a sea and a lake, so called, it is supposed, as being an ox-passage, a strait over which an ox may swim. So our northern ancestors called a strait, a sound, that is, a swim. The term Bosporus has been particularly applied to the strait between the Propontis and the Euxine, called the Thracian Bosporus; and to the strait of Caffa, called the Cimmerian Bosporus, which connects the Palus Mæotis or sea of Azof, with the Euxine. – D'Anville.