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[fruhs-tuh m] /ˈfrʌs təm/
noun, plural frustums, frusta
[fruhs-tuh] /ˈfrʌs tə/ (Show IPA).
the part of a conical solid left after cutting off a top portion with a plane parallel to the base.
the part of a solid, as a cone or pyramid, between two usually parallel cutting planes.
Origin of frustum
1650-60; < Latin: piece, bit; probably akin to Old Irish brúid (he) breaks, Old English brȳsan to crush Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2018.
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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.

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

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

    Aviation Engines

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

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

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

    The Teaching of Geometry 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.

    A. D. 2000 Alvarado M. Fuller
  • 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.

    The Light Keepers 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.

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

British Dictionary definitions for frustum


noun (pl) -tums, -ta (-tə)
  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
(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

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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