The Collaborative International Dictionary of English v.0.48:

Harbor \Har"bor\ (h[aum]r"b[~e]r), n. [Written also harbour.]
   [OE. herbor, herberwe, herberge, Icel. herbergi (cf. OHG.
   heriberga), orig., a shelter for soldiers; herr army + bjarga
   to save, help, defend; akin to AS. here army, G. heer, OHG.
   heri, Goth. harjis, and AS. beorgan to save, shelter, defend,
   G. bergen. See Harry, 2d Bury, and cf. Harbinger.]
   1. A station for rest and entertainment; a place of security
      and comfort; a refuge; a shelter.
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            [A grove] fair harbour that them seems. --Spenser.
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            For harbor at a thousand doors they knocked.
                                                  --Dryden.
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   2. Specif.: A lodging place; an inn. [Obs.] --Chaucer.
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   3. (Astrol.) The mansion of a heavenly body. [Obs.]
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   4. A portion of a sea, a lake, or other large body of water,
      either landlocked or artificially protected so as to be a
      place of safety for vessels in stormy weather; a port or
      haven.
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   5. (Glass Works) A mixing box for materials.
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   Harbor dues (Naut.), fees paid for the use of a harbor.

   Harbor seal (Zool.), the common seal.

   Harbor watch, a watch set when a vessel is in port; an
      anchor watch.
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The Collaborative International Dictionary of English v.0.48:

Harbor \Har"bor\ (h[aum]r"b[~e]r), v. t. [Written also
   harbour.] [imp. & p. p. Harbored (-b[~e]rd); p. pr. & vb.
   n. Harboring.] [OE. herberen, herberwen, herbergen; cf.
   Icel. herbergja. See Harbor, n.]
   To afford lodging to; to entertain as a guest; to shelter; to
   receive; to give a refuge to; to indulge or cherish (a
   thought or feeling, esp. an ill thought); as, to harbor a
   grudge.
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         Any place that harbors men.              --Shak.
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         The bare suspicion made it treason to harbor the person
         suspected.                               --Bp. Burnet.
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         Let not your gentle breast harbor one thought of
         outrage.                                 --Rowe.
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WordNet (r) 3.0 (2006):

harbour
    n 1: a sheltered port where ships can take on or discharge cargo
         [syn: seaport, haven, harbor, harbour]
    2: a place of refuge and comfort and security [syn: harbor,
       harbour]
    v 1: secretly shelter (as of fugitives or criminals) [syn:
         harbor, harbour]
    2: keep in one's possession; of animals [syn: harbor,
       harbour]
    3: hold back a thought or feeling about; "She is harboring a
       grudge against him" [syn: harbor, harbour, shield]
    4: maintain (a theory, thoughts, or feelings); "bear a grudge";
       "entertain interesting notions"; "harbor a resentment" [syn:
       harbor, harbour, hold, entertain, nurse]