plural -s
: a plane curve with two branches meeting at a cusp at one end of a diameter of a fixed circle, each point of the cissoid being obtained by going from the cusp along any chord to its intersection when extended with the tangent diametrically opposite the cusp and then returning along the extended chord a distance equal to the length of the chord

Word History


Late Greek kissoeidēs, from Greek, like ivy, from kissos ivy + -oeidēs -oid

Love words?

You must — there are over 200,000 words in our free online dictionary, but you are looking for one that’s only in the Merriam-Webster Unabridged Dictionary.

Start your free trial today and get unlimited access to America's largest dictionary, with:

  • More than 250,000 words that aren't in our free dictionary
  • Expanded definitions, etymologies, and usage notes
  • Advanced search features
  • Ad free!

Dictionary Entries Near cissoid

Cite this Entry

“Cissoid.” Dictionary, Merriam-Webster, Accessed 30 Sep. 2023.

Love words? Need even more definitions?

Subscribe to America's largest dictionary and get thousands more definitions and advanced search—ad free!