Source : Webster's Revised Unabridged Dictionary (1913)

Biaxal \Bi*ax"al\, Biaxial \Bi*ax"i*al\, a. [Pref. bi- + axal,
   axial.] (Opt.)
   Having two axes; as, biaxial polarization. --Brewster. --
   {Bi*ax"i*al*ly}, adv.