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In geometry, a frustum (plural: frusta or frustums) is the portion of a solid (normally a cone or pyramid) that lies between two parallel planes cutting it.
The term is commonly used in computer graphics to describe the three-dimensional region which is visible on the screen, the 'viewing frustum', which is formed by a clipped pyramid; in particular, frustum culling is a method of hidden surface determination.
In the aerospace industry, frustum is the common term for the fairing between two stages of a multistage rocket (such as the Saturn V), which is shaped like a truncated cone.