Source : Webster's Revised Unabridged Dictionary (1913)

Underbear \Un`der*bear"\, v. t. [AS. underberan. See {Under},
   and {Bear} to support.]
   1. To support; to endure. [Obs.] --Shak.

   2. To line; to guard; to face; as, cloth of gold underborne
      with blue tinsel. [Obs.] --Shak.