A cylinder is a basic curvilinear geometric shape.

Cylinder may also refer to:

• Cylinder (algebra), the Cartesian product of a set with its superset
• Cylinder (disk drive), a division of data in a disk drive
• Cylinder (engine), the space in which a piston travels in an engine
• Cylinder (firearms), the rotating part of a revolver containing multiple chambers
• Cylinder (gastropod), a subgenus of sea snails
• Cylinder (locomotive), the components that convert steam power into motion
• Cylinder (optometry)
• Cylinder, Iowa, a city in Palo Alto County, Iowa, United States
• Cylinder set, a natural basic set in product spaces
• Cylinder set measure, a way to generate a measure over product spaces
• Gas cylinder, a high-strength container for storing gases at high pressure
• Phonograph cylinder, the earliest commercial medium for recording and reproducing sound

• Cylindera, a genus of ground beetles
• All pages with titles beginning with Cylinder
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