billionth

/ˈbɪl.i.ənθ/

//ˈbɪl.i.ənθ// adj

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

The verdict

“billionth” is uncommon English (frequency #65,731 among 4,121 “B” headwords), classed as an adjective. The kind of spelling people second-guess.

#65,731
frequency rank, English
4,121
“B” headwords

According to Wiktionary data (CC BY-SA, analyzed September 3, 2026) - The ordinal form of the number one billion.

Corpus desk

Index EN-billionth · billionth · English

billionth · rank #65,731 · 0 variants · 0 confusables

  • FREQ-RARE #65,731
  • LEN-LONG 9 letters
  • VOW-3 3 vowels
  • CONFUS-0 No pairs
  • VAR-0 0 variants
  • BOOK-MID 4,121
  • PHOTO-FINISH bilirubin

Nearest frequency peer: bilirubin (-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.

Long-tail ranks near “billionth”

Sparse band: bars invert rank so rarer forms read shorter

corpus weight

What this shows Long-tail view: where “billionth” sits against similarly uncommon English ranks.

Source FrequencyWords open word-frequency list As of September 3, 2026
Key facts for billionth
PropertyValue
Headwordbillionth
LanguageEnglish
Part of speechAdjective
IPA/ˈbɪl.i.ənθ/
Letters9
Frequency rank#65,731
Misspellings tracked0
Confusable pairs0
SourceWiktionary (kaikki.org)

Long-tail rank of “billionth” in English

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

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

The axis is logarithmic, with each marked tick roughly ten times rarer than the last. Rare peers in the same band: “bilirubin” (#65,730), “bioenergy” (#65,732), “biked” (#65,729). Among 4,121 “B” headwords, “billionth” is #65,731. Source: FrequencyWords open word-frequency list.

Rare enough to double-check

billionth is uncommon English at frequency #65,731 among 4,121 “B” headwords, classed as anadjective, transcribed /ˈbɪl.i.ənθ/. Rarity is why readers land here mid-draft. Gloss: "The ordinal form of the number one billion.".

Our edit-distance generator produced no likely misspellings for billionth, a straightforward case of a spelling with little room for common typos. Our dataset records no confusable match here, suggesting its spelling stands apart enough that readers rarely confuse it with something else.

Etymologically, the entry records: From billion + -th (ordinal suffix). The correct English form is billionth, spelled B-I-L-L-I-O-N-T-H.

Definition

  1. 1
    The ordinal form of the number one billion.

Etymology

From billion + -th (ordinal suffix).

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); frequency ordering uses the FrequencyWords open word-frequency list (2018 English corpus, MIT). See the methodology for how each field is sourced and updated.

Frequently Asked Questions

How do you spell "billionth"?
"billionth" is spelled B-I-L-L-I-O-N-T-H. The IPA pronunciation is /ˈbɪl.i.ənθ/.
What does "billionth" mean?
As an adjective, "billionth" means: The ordinal form of the number one billion.
How do you pronounce "billionth"?
The IPA (International Phonetic Alphabet) transcription for "billionth" is /ˈbɪl.i.ənθ/. 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 "billionth"?
From billion + -th (ordinal suffix). 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 "billionth", not the corpus desk frequency band.

Same letter count

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

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

Source: FrequencyWords open word-frequency list