Definition of equant in English:

Share this entry


Pronunciation: /ˈiːkwənt/


Astronomy , historical
(In the Ptolemaic system) an imaginary circle introduced with the purpose of reconciling the planetary movements with the hypothesis of uniform circular motion.
Example sentences
  • When the intricacies of epicycles, deferents and equants were explained to him Alfonso ‘the Wise’ is said to have remarked that if the Almighty had consulted him on the matter, he would have recommended something a little simpler…
  • If you had asked Aristotle or Ptolemy to explain how planets move, you would have got a lecture on epicycles and equants.
  • Gingerich noted ‘the majority of sixteenth-century astronomers thought eliminating the equant was Copernicus' big achievement.’


(Of a crystal or particle) having its different diameters approximately equal, so as to be roughly cubic or spherical in shape.
Example sentences
  • It typically occurs as transparent flattened crystals, as small equant crystals, as intergrown masses of small lustrous crystals, and occasionally as stout or elongated twinned crystals.
  • A few outstanding composite specimens were recovered, with crude dendritic copper intergrown with one or two large, single, equant crystals.
  • Doubly terminated, transparent, colorless equant crystals of classic Herkimer ‘diamond’ habit are locally common.


Mid 16th century: from Latin aequant- 'making equal', from the verb aequare.

For editors and proofreaders

Line breaks: equant

Share this entry

What do you find interesting about this word or phrase?

Comments that don't adhere to our Community Guidelines may be moderated or removed.