Answer:
biquadratic polynomial
Explanation:
The given polynomial is

The degree of this polynomial (the highest power) is 4
Such a polynomial is called a quartic polynomial. If all the terms have even degree, which in this case is true since there is only one term and its degree is 4 it is called a biquadratic polynomial
If polynomial has degree 1 ex 4x + 3 it is called a linear polynomial
If it has degree 2 --> quadratic
If it has degree 3 --> cubic