rhombus

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/

• Audio (AUS)

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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.

• (geometry): diamond (not in technical use), lozenge (if not square), rhomb

• (geometry): rhombohedron

• rhombus star

• “rhombus”, in OneLook Dictionary Search.
• “rhombus”, in The Century Dictionary […], New York, N.Y.: The Century Co., 1911, →OCLC.

• rombus, rumbus (Medieval Latin)

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

• (Classical) IPA^(key): /ˈrom.bus/, [ˈrɔmbʊs̠]
• (modern Italianate Ecclesiastical) IPA^(key): /ˈrom.bus/, [ˈrɔmbus]

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.

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

Borrowings

• “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