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# frustum

[fruhs-tuh m] /ˈfrʌs təm/
noun, plural frustums, frusta
[fruhs-tuh] /ˈfrʌs tə/ (Show IPA).
Geometry.
1.
the part of a conical solid left after cutting off a top portion with a plane parallel to the base.
2.
the part of a solid, as a cone or pyramid, between two usually parallel cutting planes.
Origin of frustum
1650-1660
1650-60; < Latin: piece, bit; probably akin to Old Irish brúid (he) breaks, Old English brȳsan to crush
Dictionary.com Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2017.
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Examples from the Web for frustum
Historical Examples
• Wa'al, jest cut off the top, and what's left will be the frustum.

James Otis
• Then follows, in most textbooks, a theorem relating to the volume of a frustum.

David Eugene Smith
• The top of the piston forms the frustum of the cone and the pistons are 110 mm.

Victor Wilfred Pag
• A stick of timber is in the shape of the frustum of a square pyramid, the lower base being 22 in.

Edward L. Thorndike
• This leads to the corollary concerning the lateral area of the frustum of a regular pyramid.

David Eugene Smith
• If the upper base is equal to the lower base, the frustum becomes a cylinder, and still the proposition remains true.

David Eugene Smith
• The vessel proper was a cylinder; its base, a plane; its top, the frustum of a cone, surmounted by a tower upon a tower.

• It was built in the form of a frustum of a pyramid, and was fifty-four feet square at the bottom and six feet square at the top.

James Otis
• It is 56 feet high from the rock to the platform or balcony floor, and its shape is the frustum of a cone.

Robert Stevenson
• The solids divided in given ratios are the sphere, the pyramid, the cone and a frustum thereof.

Various
British Dictionary definitions for frustum

## frustum

/ˈfrʌstəm/
noun (pl) -tums, -ta (-tə)
1.
(geometry)
1. the part of a solid, such as a cone or pyramid, contained between the base and a plane parallel to the base that intersects the solid
2. the part of such a solid contained between two parallel planes intersecting the solid
2.
(architect) a single drum of a column or a single stone used to construct a pier
Word Origin
C17: from Latin: piece; probably related to Old English brӯsan to crush, bruise
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition
© William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins
Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012
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Word Origin and History for frustum
n.

1650s, from Latin frustum "piece broken off," from PIE *bhrus-to-, from root *bhreu- "to cut, break up."

Online Etymology Dictionary, © 2010 Douglas Harper
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### Difficulty index for frustum

Few English speakers likely know this word

### Word Value for frustum

12
15
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