biquadratic adjective & noun. 
[bʌɪkwɒ'dratɪk] M17.[from BI- + QUADRATIC.]Math.A. adjective. Of, pertaining to, or containing the fourth power (or root) of a number. 
M17.b. noun. A biquadratic equation. Formerly also, the fourth power of a number. 
M17.Also 
 ■   biquadrate adjective & noun L17-E19.  [TahlilGaran] English Dictionary ▲