(mathematics) Of a polynomial expression, involving only the second, third and fourth powers of a variable, as x⁴ + 3x² + 2. Sometimes extended to any expression involving the biquadrate or fourth power (but no higher powers), as x⁴ − 4x³ + 3x² − x + 1.

(mathematics) A biquadratic equation.

In a biquadratic way.

plural of biquadratic