irrational number

noun

"irrational-number" is a 16-letter English headword indexed on PlainSpell.

The verdict

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

Unranked
below top-frequency English
17
letters

According to Wiktionary data (CC BY-SA, analyzed September 3, 2026) - Any real number that cannot be expressed as a ratio of two integers.

Corpus desk

Index EN-irrational-number · irrational number · English

irrational number · unranked · 0 variants · 0 confusables

  • FREQ-UNRANKED Unranked
  • LEN-MEGA 17 letters
  • VOW-7 7 vowels
  • CONFUS-0 No pairs
  • VAR-0 0 variants
  • BOOK-THIN "I" 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 irrational number
PropertyValue
Headwordirrational number
LanguageEnglish
Part of speechNoun
Letters17
Misspellings tracked0
Confusable pairs0
SourceWiktionary (kaikki.org)

Long-tail rank of “irrational number” in English

irrational numberranks 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

irrational number is uncommon English outside the top frequency list, classed as anoun. Rarity is why readers land here mid-draft. Gloss: "Any real number that cannot be expressed as a ratio of two integers.".

irrational number has no tracked misspelling variants, a sign its spelling follows regular English conventions. This headword has no recorded confusable partner, since its spelling is unusual enough that it doesn't cluster with a lookalike.

Our source data has no etymology on file for this entry, so spelling patterns must be inferred from the word's phoneme-to-grapheme mapping rather than from a documented borrowing chain. The correct English form is irrational number, spelled I-R-R-A-T-I-O-N-A-L- -N-U-M-B-E-R.

Definition

  1. 1
    Any real number that cannot be expressed as a ratio of two integers.

Recorded use

Wiktionary example

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

  1. The square root of a positive integer is an irrational number unless the positive integer is a perfect square, in which case the square root will also be a positive integer.

Antonyms

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 "irrational number"?
"irrational number" is spelled I-R-R-A-T-I-O-N-A-L- -N-U-M-B-E-R.
What does "irrational number" mean?
As a noun, "irrational number" means: Any real number that cannot be expressed as a ratio of two integers.
What language does "irrational number" come from?
"irrational number" is a English word. PlainSpell covers definitions, pronunciations, and spelling data across English, Spanish, Portuguese, French, and German.
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