sylinder

Sylinder is a term that is sometimes encountered as an alternate spelling of cylinder, particularly in non-English contexts or as a transliteration. In standard English, the correct spelling is cylinder. The word can refer to both a geometric shape and a mechanical component.

In geometry, a cylinder is a solid formed by moving a straight line parallel to a fixed direction along a curve that traces a circle; equivalently, it can be described as the set of all points whose projection onto a given plane is a circle and whose height is perpendicular to that plane. The canonical case is the circular cylinder, with two parallel circular bases and a curved surface connecting them. Cylinders can be right or oblique, and their bases can be circles or other similar shapes such as ellipses (elliptical cylinders).

In engineering and physics, a cylinder often refers to a chamber in which a piston moves, such as a piston cylinder in an internal combustion engine, a hydraulic cylinder, or a pneumatic cylinder. These devices convert pressure or fluid movement into linear motion and force. Formulas for volume and surface area depend on the base shape: for a circular cylinder, volume is base area (pi r^2) times height, lateral surface area is circumference (2 pi r) times height, and total surface area is 2 pi r^2 plus 2 pi r h.

Etymology and usage notes: the English term derives from Latin via French and Greek roots; orthography varies by language. The term "sylinder" may appear in non-English texts or as a transliteration. For technical writing, prefer "cylinder" unless quoting a source that uses the alternate spelling.