isosceles

/aɪˈsɒsəliːz/

//aɪˈsɒsəliːz// adj

By · According to Wiktionary data (CC BY-SA) ·

"isosceles" is a 9-letter English headword indexed on PlainSpell.

The verdict

“isosceles” is uncommon English (frequency #74,204 among 17,902 “I” headwords), classed as an adjective. The kind of spelling people second-guess.

#74,204
frequency rank, English
17,902
“I” headwords

According to Wiktionary data (CC BY-SA, analyzed May 6, 2026) - Having (at least) two sides of equal length, used especially of a triangle or trapezoid.

Corpus desk

Index EN-isosceles · isosceles · English

isosceles · rank #74,204 · 0 variants · 0 confusables

  • FREQ-RARE #74,204
  • LEN-LONG 9 letters
  • VOW-4 4 vowels
  • CONFUS-0 No pairs
  • VAR-0 0 variants
  • BOOK-DENSE 17,902
  • PHOTO-FINISH Ishihara

Nearest frequency peer: Ishihara (-1 rank slots)

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.

Frequency neighbourhood for “isosceles”

Lower corpus rank = more everyday usage (inverted bar length for readability)

corpus weight

What this shows Bars show where “isosceles” sits against the nearest ranked English headwords in the FrequencyWords band, not a reprint of letter-browse containment.

Source FrequencyWords open word-frequency list As of May 6, 2026
Key facts for isosceles
PropertyValue
Headwordisosceles
LanguageEnglish
Part of speechAdjective
IPA/aɪˈsɒsəliːz/
Letters9
Frequency rank#74,204
Misspellings tracked0
Confusable pairs0
SourceWiktionary (kaikki.org)

Where “isosceles” sits in English frequency

Every-word frequency runs from the handful of words we use constantly (left) to the long tail used once in a blue moon (right). isosceles lands here:

#1#100#1K#10K#100K
← used constantlyrarely used →

Scale is logarithmic (each tick is 10× rarer). Source: FrequencyWords open word-frequency list.

Rare enough to double-check

isosceles is uncommon English at frequency #74,204 among 17,902 “I” headwords, classed as anadjective, transcribed /aɪˈsɒsəliːz/. Rarity is why readers land here mid-draft. Gloss: "Having (at least) two sides of equal length, used especially of a triangle or trapezoid.".

We couldn't generate a plausible misspelling set for isosceles, suggesting the orthography follows predictable English patterns. Our confusable-pair dataset has no match for it, which tends to mean the word is visually distinctive enough to stand on its own.

Etymologically, the entry records: Borrowed from Latin īsoscelēs, from Ancient Greek ἰσοσκελής (isoskelḗs, “equal-legged”), from ἴσος (ísos, “equal”) + σκέλος (skélos, “leg”) + -ής (-ḗs, adjective suffix). See also iso-. The correct English form is isosceles, spelled I-S-O-S-C-E-L-E-S.

Definition

  1. 1
    Having (at least) two sides of equal length, used especially of a triangle or trapezoid.

Recorded use

Wiktionary examples

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

  1. Upon each exterior side draw an Isosceles Triangle of 480 Fathoms.
  2. A right double pyramid is isosceles when the extremities of the vertex-edge are at the same distance from the plane of the base.

Etymology

Borrowed from Latin īsoscelēs, from Ancient Greek ἰσοσκελής (isoskelḗs, “equal-legged”), from ἴσος (ísos, “equal”) + σκέλος (skélos, “leg”) + -ής (-ḗs, adjective suffix). See also iso-.

This word in other languages

isósceles(Español)isocèle(Français)gleichschenklig(Deutsch)

Definitions, pronunciation, and etymology for this entry are drawn from Wiktionary via the kaikki.org structured extract (CC BY-SA); frequency ordering uses the FrequencyWords open word-frequency list (2018 English corpus, MIT). See the methodology for how each field is sourced and updated.

PlainSpell is rendered directly from structured Wiktionary extracts and open word-frequency lists, no number is typed in by an editor. See our editorial standards & corrections policy, the methodology behind these numbers, or report a data error. Data current as of May 6, 2026. Primary sources: Wiktionary (via kaikki.org) and FrequencyWords.

Frequently Asked Questions

How do you spell "isosceles"?
"isosceles" is spelled I-S-O-S-C-E-L-E-S. The IPA pronunciation is /aɪˈsɒsəliːz/.
What does "isosceles" mean?
As an adjective, "isosceles" means: Having (at least) two sides of equal length, used especially of a triangle or trapezoid.
How do you pronounce "isosceles"?
The IPA (International Phonetic Alphabet) transcription for "isosceles" is /aɪˈsɒsəliːz/. Click the speaker icon on the pronunciation badge above to hear it spoken aloud where audio is available.
What is the origin of the word "isosceles"?
Borrowed from Latin īsoscelēs, from Ancient Greek ἰσοσκελής (isoskelḗs, “equal-legged”), from ἴσος (ísos, “equal”) + σκέλος (skélos, “leg”) + -ής (-ḗs, adjective suffix). See also iso-. 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.

Similar English words by spelling shape

Same letter count and similar misspelling depth for "isosceles", not the corpus desk frequency band.

Same letter count

Frequency-ranked English headwords with 9 letters (nearest by frequency rank).

Hildegard#74,168Kosciusko#74,240lawyering#74,258grimacing#74,138
Data Source

Wiktionary (via kaikki.org), licensed under CC BY-SA & GFDL. Word ordering uses an open word-frequency list; misspelling variants are generated by edit-distance from the correct headword.

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

Source: FrequencyWords open word-frequency list