Rotations in 4-dimensional Euclidean space
In mathematics, the group of rotations about a fixed point in four-dimensional Euclidean space is denoted SO(4). The name comes from the fact that it is the special orthogonal group of order 4.
https://en.wikipedia.org/wiki/Rotations_in_4-dimensional_Euclidean_space#Geometry_of_4D_rotations