Source : Webster's Revised Unabridged Dictionary (1913)

Incesttuous \In*cest"tu*ous\ (?; 135), a. [L. incestuosus: cf.
   F. incestueux.]
   Guilty of incest; involving, or pertaining to, the crime of
   incest; as, an incestuous person or connection. --Shak.

         Ere you reach to this incestuous love, You must divine
         and human rights remove.                 --Dryden.
   -- {In*cest"tu*ous*ly}, adv. -- {In*cest"tu*ous*ness}, n.