oblique coordinate system
A coordinate system in which the axes are not perpendicular. Used in mathematics, especially in geometry and linear algebra.
In an oblique coordinate system, the basis vectors are not orthogonal.
直交座標系 is an orthogonal coordinate system where axes are perpendicular, while 斜交座標系 has non-perpendicular axes.
Compound of 斜交 (oblique intersection) + 座標系 (coordinate system). The term is a direct technical translation of the English 'oblique coordinate system'.