biquadrate

from WordNet (r) 3.0 (2006)

biquadrate
    n 1: an algebraic equation of the fourth degree [syn:
         {biquadrate}, {biquadratic}, {quartic}, {fourth power}]

from The Collaborative International Dictionary of English v.0.48

Biquadrate \Bi*quad"rate\, n. [Pref. bi- + quadrate.] (Math.)
   The fourth power, or the square of the square. Thus 4x4=16,
   the square of 4, and 16x16=256, the biquadrate of 4.
   [1913 Webster]