Turning is a engineering vowin.cn/en/News/news1251.html' target='_blank'>machining process in which a cutting tool, typically a non-rotary tool bit, describes a helical toolpath by moving more or less linearly while the workpiece rotates.
The tool's axes of movement may be literally a straight line,
or they may be along some set of curves or angles, but they are essentially linear (in the nonmathematical sense).