The Collaborative International Dictionary of English v.0.48:

Overbear \O`ver*bear"\, v. t.
   1. To bear down or carry down, as by excess of weight, power,
      force, etc.; to overcome; to suppress.
      [1913 Webster]

            The point of reputation, when the news first came of
            the battle lost, did overbear the reason of war.
                                                  --Bacon.
      [1913 Webster]

            Overborne with weight the Cyprians fell. --Dryden.
      [1913 Webster]

            They are not so ready to overbear the adversary who
            goes out of his own country to meet them. --Jowett
                                                  (Thucyd. )
      [1913 Webster]

   2. To domineer over; to overcome by insolence.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Overbear \O`ver*bear"\, v. i.
   To bear fruit or offspring to excess; to be too prolific.
   [1913 Webster]

WordNet (r) 3.0 (2006):

overbear
    v 1: overcome; "overbear criticism, protest, or arguments"
    2: bear too much
    3: contract the abdominal muscles during childbirth to ease
       delivery [syn: bear down, overbear]