The Collaborative International Dictionary of English v.0.48:

Jamb \Jamb\, Jambe \Jambe\, Jambeau \Jambeau\, n.
   See Jambes.
   [PJC]

The Collaborative International Dictionary of English v.0.48:

Jamb \Jamb\, n. [Prov. E. jaumb, jaum, F. jambe a leg, jambe de
   force a principal rafter. See Gambol.]
   [1913 Webster]
   1. (Arch) The vertical side of any opening, as a door or
      fireplace; hence, less properly, any narrow vertical
      surface of wall, as the of a chimney-breast or of a pier,
      as distinguished from its face. --Gwilt.
      [1913 Webster]

   2. (Mining) Any thick mass of rock which prevents miners from
      following the lode or vein.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Jamb \Jamb\, v. t.
   See Jam, v. t. & i.
   [1913 Webster] Jambe
   Jamb

WordNet (r) 3.0 (2006):

jamb
    n 1: upright consisting of a vertical side member of a door or
         window frame