Source : Webster's Revised Unabridged Dictionary (1913)

Seaport \Sea"port`\ (s[=e]"p[=o]rt`), n.
   A port on the seashore, or one accessible for seagoing
   vessels. Also used adjectively; as, a seaport town.

Source : WordNet®

seaport
     n : a sheltered port where ships can take on or discharge cargo
         [syn: {haven}, {harbor}, {harbour}]