The Collaborative International Dictionary of English v.0.48:

Hellespont \Hel"les*pont\, n. [L. Hellespontus, Gr. ?; ? the
   mythological Helle, daughter of Athamas + ? sea.]
   A narrow strait between Europe and Asia, now called the
   Daradanelles. It connects the Aegean Sea and the sea of
   Marmora.
   [1913 Webster]

WordNet (r) 3.0 (2006):

Hellespont
    n 1: the strait between the Aegean and the Sea of Marmara that
         separates European Turkey from Asian Turkey [syn:
         Dardanelles, Canakkale Bogazi, Hellespont]