irrational number

noun

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

The verdict

“irrational number” is outside the top-ranked English vocabulary, used as a noun - the kind of word writers most often double-check.

Unranked
below top-frequency English
17
letters

According to Wiktionary data (CC BY-SA, analyzed May 6, 2026) - Any real number that cannot be expressed as a ratio of two integers.

Key facts for irrational number
PropertyValue
Headwordirrational number
LanguageEnglish
Part of speechNoun
Letters17
Misspellings tracked0
Confusable pairs0
SourceWiktionary (kaikki.org)

Where “irrational number” sits in English frequency

irrational number falls outside the top-100,000 ranked English words, the long-tail zone of technical, archaic, or low-frequency vocabulary, exactly where readers second-guess spellings most.

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

Spelling & Dictionary Insight

The English entry for irrational number is 17 letters long, classified as a noun. It sits outside the most-frequent rank tiers, which is often why uncommon words generate more spelling variants per reader. The dominant gloss from Wiktionary reads: "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.

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.

Using “irrational number”

The practical upshot for anyone who landed here from a spell-check.

  • The one correct English spelling is I-R-R-A-T-I-O-N-A-L- -N-U-M-B-E-R - every other letter order is a misspelling in standard orthography.
  • Browse more English words and confusable pairs in the same reference. English words
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 FrequencyWords open word-frequency list