in geography, denotes, in general, a narrow sea, or channel, separating two continents, and serving as a communication between two seas.

Bosphorus is more particularly used for the straits of Constantinople, which divides Europe from Asia.

This was the original Bosphorus; so called because oxen could swim over it: And from the resemblance between it and the straits of Kaffa, these last were anciently called the Cimmerian, as the former were the Thracian Bosphorus.