[rom-buh s]
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noun, plural rhom·bus·es, rhom·bi [rom-bahy] /ˈrɒm baɪ/.
  1. an oblique-angled equilateral parallelogram; any equilateral parallelogram except a square.
  2. an equilateral parallelogram, including the square as a special case.
  3. a rhombohedron.

Origin of rhombus

1560–70; < Latin < Greek rhómbos anything that may be spun around, derivative of rhémbein to revolve
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

British Dictionary definitions for rhombi


noun plural -buses or -bi (-baɪ)
  1. an oblique-angled parallelogram having four equal sidesAlso called: rhomb Compare square (def. 1)

Word Origin for rhombus

C16: from Greek rhombos something that spins; related to rhembein to whirl
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

Word Origin and History for rhombi



1560s, from Late Latin rhombus, from Greek rhombos "rhombus, rhomb, lozenge; spinning top, maghic wheel used by sorcerers; a spinning motion," from rhembesthai "to spin, whirl," from PIE *wrembh-, from *werbh- "to turn, twist, bend" (cf. Old English weorpan "to throw away"), from root *wer- (3) "to turn, bend" (see versus).

Online Etymology Dictionary, © 2010 Douglas Harper

rhombi in Science


Plural rhombuses rhombi (rŏm)
  1. A parallelogram with four equal sides; an equilateral parallelogram.
Related formsrhomboid, rhomboidal adjective
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.