Bosporus /(bŏs"pō̇*rŭs)/

Bos·po·rus

Bosporus

n.
  1. A strait or narrow sea between two seas, or a lake and a seas; as, the Bosporus (formerly the Thracian Bosporus) or Strait of Constantinople, between the Black Sea and Sea of Marmora; the Cimmerian Bosporus, between the Black Sea and Sea of Azof.