The Collaborative International Dictionary of English v.0.48:

Port \Port\, n. [AS. port, L. portus: cf. F. port. See Farm,
   v., Ford, and 1st, 3d, & 4h Port.]
   1. A place where ships may ride secure from storms; a
      sheltered inlet, bay, or cove; a harbor; a haven. Used
      also figuratively.
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            Peering in maps for ports and piers and roads.
                                                  --Shak.
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            We are in port if we have Thee.       --Keble.
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   2. In law and commercial usage, a harbor where vessels are
      admitted to discharge and receive cargoes, from whence
      they depart and where they finish their voyages.
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   Free port. See under Free.

   Port bar. (Naut,)
      (a) A boom. See Boom, 4, also Bar, 3.
      (b) A bar, as of sand, at the mouth of, or in, a port.

   Port charges (Com.), charges, as wharfage, etc., to which a
      ship or its cargo is subjected in a harbor.

   Port of entry, a harbor where a customhouse is established
      for the legal entry of merchandise.

   Port toll (Law), a payment made for the privilege of
      bringing goods into port.

   Port warden, the officer in charge of a port; a harbor
      master.
      [1913 Webster]

WordNet (r) 3.0 (2006):

port of entry
    n 1: a port in the United States where customs officials are
         stationed to oversee the entry and exit of people and
         merchandise [syn: port of entry, point of entry]