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See also: Rhombus


 rhombus on Wikipedia
A pair of rhombi.
A rhombus (flatfish)


Learned borrowing from Latin rhombus, from Ancient Greek ῥόμβος (rhómbos, rhombus, spinning top). Doublet of rhomb and rhumb.


  • (UK) IPA(key): /ˈɹɒmbəs/
  • (US) IPA(key): /ˈɹɑːmbəs/
  • (file)


rhombus (plural rhombi or rhombuses)

  1. (geometry) A parallelogram having all sides of equal length. [from 16th c.]
    1. The rhombus diamond, as one of the suits seen in a deck of playing cards (♦ or ♦).
  2. In early Greek religion, an instrument whirled on the end of a string similar to a bullroarer.
    • 1936, Rollo Ahmed, The Black Art, London: Long, page 58:
      The Greeks also used an instrument called a rhombus, or witches' wheel. As the wheel spun round, it was thought that influence was gained over certain people or circumstances.
  3. (zoology, now rare) Any of several flatfishes, including the brill and turbot, once considered part of the genus Rhombus, now in Scophthalmus. [from 16th c.]
    • 1638, Thomas Herbert, Some Yeares Travels, section I:
      the greedy Tuberon or Shark arm'd with a double row of venemous teeth pursues them, directed by a little Rhombus, Musculus or pilot-fish that scuds to and fro to bring intelligence [...].
  4. (zoology, archaic) Snails, now in genus Conus or family Conidae.



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From Ancient Greek ῥόμβος (rhómbos, rhombus, spinning top), from ῥέμβω (rhémbō, I turn around).



rhombus m (genitive rhombī); second declension

  1. rhombus (geometry)
  2. flatfish
  3. a magician's circle
  4. (Medieval Latin) sturgeon
    Synonym: sturiō
    Hyponym: carrocō


Second-declension noun.

Case Singular Plural
Nominative rhombus rhombī
Genitive rhombī rhombōrum
Dative rhombō rhombīs
Accusative rhombum rhombōs
Ablative rhombō rhombīs
Vocative rhombe rhombī


  • Catalan: rom
  • Portuguese: rumo
  • Spanish: rumbo, romo
  • Sicilian: rummu


  • rhombus”, in Charlton T. Lewis and Charles Short (1879) A Latin Dictionary, Oxford: Clarendon Press
  • rhombus”, in Charlton T. Lewis (1891) An Elementary Latin Dictionary, New York: Harper & Brothers
  • rhombus in Charles du Fresne du Cange’s Glossarium Mediæ et Infimæ Latinitatis (augmented edition with additions by D. P. Carpenterius, Adelungius and others, edited by Léopold Favre, 1883–1887)
  • rhombus in Gaffiot, Félix (1934) Dictionnaire illustré latin-français, Hachette.
  • rhombus”, in Harry Thurston Peck, editor (1898), Harper's Dictionary of Classical Antiquities, New York: Harper & Brothers
  • rhombus”, in William Smith et al., editor (1890), A Dictionary of Greek and Roman Antiquities, London: William Wayte. G. E. Marindin