cissoid

noun

"cissoid" is a 7-letter English headword indexed on PlainSpell.

The verdict

“cissoid” is uncommon English (outside the top frequency list), classed as a noun. The kind of spelling people second-guess.

Unranked
below top-frequency English
7
letters

According to Wiktionary data (CC BY-SA, analyzed September 3, 2026) - Any of a family of curves defined as the locus of a point, P, on a line from a given fixed point and intersecting two given curves, C₁ and C₂, where the distance along the line from C₁ to P remains...

Corpus desk

Index EN-cissoid · cissoid · English

cissoid · unranked · 0 variants · 0 confusables

  • FREQ-UNRANKED Unranked
  • LEN-LONG 7 letters
  • VOW-3 3 vowels
  • CONFUS-0 No pairs
  • VAR-0 0 variants
  • BOOK-THIN "C" thin
  • PHOTO-UNK Peer pending

Read with this headword: Spelling guide for this pattern

Desk codes from Wiktionary headword shape, FrequencyWords rank tier, confusable-pair count, generated misspelling depth, letter-cohort book size, and photo-finish peer. Not a difficulty grade.

Key facts for cissoid
PropertyValue
Headwordcissoid
LanguageEnglish
Part of speechNoun
Letters7
Misspellings tracked0
Confusable pairs0
SourceWiktionary (kaikki.org)

Long-tail rank of “cissoid” in English

cissoidranks outside the top 100,000 English headwords, in the long tail of specialist, archaic, or seldom-used vocabulary, exactly the territory where a reader stops mid-sentence to double-check spelling.

Beyond rank #100,000. Source: FrequencyWords open word-frequency list.

Rare enough to double-check

cissoid is uncommon English outside the top frequency list, classed as anoun. Rarity is why readers land here mid-draft. Gloss: "Any of a family of curves defined as the locus of a point, P, on a line from a given fixed point and intersecting two given curves, C₁ and C₂, where the distance along the line from C₁ to P remains...".

We couldn't generate a plausible misspelling set for cissoid, a straightforward case of a spelling with little room for common typos. Our dataset records no confusable match here, a sign it's visually distinctive enough not to be mixed up with another word.

Etymologically, the entry records: From Ancient Greek κισσός (kissós, “ivy”) + εἶδος (eîdos, “form, image”). The correct English form is cissoid, spelled C-I-S-S-O-I-D.

Definition

  1. 1
    Any of a family of curves defined as the locus of a point, P, on a line from a given fixed point and intersecting two given curves, C₁ and C₂, where the distance along the line from C₁ to P remains constant and equal to the distance from P to C₂.

Recorded use

Wiktionary example

These source excerpts show how cissoid appears in context. They illustrate usage; the definition above remains the entry’s reference meaning.

  1. The cissoid of a circle and a line is a conchoid

Etymology

From Ancient Greek κισσός (kissós, “ivy”) + εἶδος (eîdos, “form, image”).

This word in other languages

Definitions, pronunciation, and etymology for this entry are drawn from Wiktionary via the kaikki.org structured extract (CC BY-SA). See the methodology for how each field is sourced and updated.

Frequently Asked Questions

How do you spell "cissoid"?
"cissoid" is spelled C-I-S-S-O-I-D.
What does "cissoid" mean?
As a noun, "cissoid" means: Any of a family of curves defined as the locus of a point, P, on a line from a given fixed point and intersecting two given curves, C₁ and C₂, where the distance along the line from C₁ to P remains...
What is the origin of the word "cissoid"?
From Ancient Greek κισσός (kissós, “ivy”) + εἶδος (eîdos, “form, image”). See the full etymology section above for more details.
Is PlainSpell free to use?
Yes, PlainSpell is a completely free word reference. You can look up definitions, pronunciations, confusable pairs, homophones, and spelling corrections across 5 languages without any sign-up or subscription.

Source: Wiktionary (via kaikki.org) Structured Wiktionary extract

Source: FrequencyWords open word-frequency list