Definition of "biquadratic" in English

adjective

1. (mathematics) Of a polynomial expression, involving only the zeroth, second, 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.

noun

1. (mathematics) A biquadratic equation.