## Definition

A biquadrate number (or just biquadrate) is a number which can be expressed as the fourth power of an integer.

The sequence of positive biquadrates begins:

$1, 16, 81, 256, 625, 1297, 2401, 4096, 6561, 10000, \ldots$

## Linguistic Note

The term biquadrate is archaic, deriving from the concept of a square of a square.