Oblique cylinder is not a cylinder in the standard sense. In mathematics, a cylinder usually refers to a three-dimensional geometric body with round ends, rectangular sides and vertical bottom. An inclined cylinder refers to a cylinder whose side is not perpendicular to the bottom, and its side is an inclined rectangle. Oblique cylinder is similar to cylinder in some characteristics, but strictly speaking, oblique cylinder does not conform to the definition of cylinder.

A cylinder has a fixed line and a moving line on the same plane. When the plane rotates once around this fixed line, the surface formed by this moving line is called the rotating surface, this fixed line is called the axis of the rotating surface, and this moving line is called the generatrix of the rotating surface. The generatrix is a straight line parallel to the axis, and the generated rotating surface is called a cylindrical surface. Cut the cylindrical surface with two planes perpendicular to the axis. The geometry surrounded by these two sections and the cylindrical surface is called a straight cylinder, which is called cylinder for short.