cosmonaut

/ˈkɒz.məˌnɔːt/

//ˈkɒz.məˌnɔːt// noun

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

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

The verdict

“cosmonaut” is uncommon English (frequency #52,241 among 5,599 “C” headwords), classed as a noun. The kind of spelling people second-guess.

#52,241
frequency rank, English
5,599
“C” headwords

According to Wiktionary data (CC BY-SA, analyzed September 3, 2026) - An astronaut, especially a Russian or Soviet one.

Corpus desk

Index EN-cosmonaut · cosmonaut · English

cosmonaut · rank #52,241 · 0 variants · 0 confusables

  • FREQ-RARE #52,241
  • LEN-LONG 9 letters
  • VOW-4 4 vowels
  • CONFUS-0 No pairs
  • VAR-0 0 variants
  • BOOK-DENSE 5,599
  • PHOTO-FINISH cosine

Nearest frequency peer: cosine (-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 “cosmonaut”

Sparse band: bars invert rank so rarer forms read shorter

corpus weight

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

Source FrequencyWords open word-frequency list As of September 3, 2026
Key facts for cosmonaut
PropertyValue
Headwordcosmonaut
LanguageEnglish
Part of speechNoun
IPA/ˈkɒz.məˌnɔːt/
Letters9
Frequency rank#52,241
Misspellings tracked0
Confusable pairs0
SourceWiktionary (kaikki.org)

Long-tail rank of “cosmonaut” in English

This scale runs from the tiny cluster of words that carry ordinary speech (left) to the long tail of words almost nobody reaches for (right).cosmonautfalls 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: “cosine” (#52,240), “Cottrell” (#52,243), “countable” (#52,244). Among 5,599 “C” headwords, “cosmonaut” is #52,241. Source: FrequencyWords open word-frequency list.

Rare enough to double-check

cosmonaut is uncommon English at frequency #52,241 among 5,599 “C” headwords, classed as anoun, transcribed /ˈkɒz.məˌnɔːt/. Rarity is why readers land here mid-draft. Gloss: "An astronaut, especially a Russian or Soviet one.".

cosmonaut has no tracked misspelling variants, and the word's spelling is regular enough that our generator found nothing worth flagging. Our confusable-pair dataset has no match for it, since its spelling is unusual enough that it doesn't cluster with a lookalike.

Etymologically, the entry records: Borrowed from Russian космона́вт (kosmonávt), from Ancient Greek κόσμος (kósmos, “universe”) + ναύτης (naútēs, “sailor”), may be decomposed as cosmo- + -naut. The correct English form is cosmonaut, spelled C-O-S-M-O-N-A-U-T.

Definition

  1. 1
    An astronaut, especially a Russian or Soviet one.

Recorded use

Wiktionary examples

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

  1. Khrushchev’s answer came 60 years ago, on April 12, 1961, when Soviet cosmonaut Yuri Gagarin circled the Earth aboard a spacecraft called Vostok 1.
  2. Longtime NASA astronaut Don Pettit, who has ventured to space four times, returned to Earth on Saturday night from the International Space Station. Pettit, who turned 70 on Sunday, landed at 9:20 p.m. ET in a Soyuz spacecraft with Roscosmos cosmonauts Alexey Ovchinin and Ivan Vagner near Zhezkazgan, Kazakhstan, after a seven-month stay aboard the orbiting…

Etymology

Borrowed from Russian космона́вт (kosmonávt), from Ancient Greek κόσμος (kósmos, “universe”) + ναύτης (naútēs, “sailor”), may be decomposed as cosmo- + -naut.

This word in other languages

cosmonauta(Español)cosmonaute(Français)Kosmonaut(Deutsch)cosmonauta(Português)

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 "cosmonaut"?
"cosmonaut" is spelled C-O-S-M-O-N-A-U-T. The IPA pronunciation is /ˈkɒz.məˌnɔːt/.
What does "cosmonaut" mean?
As a noun, "cosmonaut" means: An astronaut, especially a Russian or Soviet one.
How do you pronounce "cosmonaut"?
The IPA (International Phonetic Alphabet) transcription for "cosmonaut" is /ˈkɒz.məˌnɔːt/. 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 "cosmonaut"?
Borrowed from Russian космона́вт (kosmonávt), from Ancient Greek κόσμος (kósmos, “universe”) + ναύτης (naútēs, “sailor”), may be decomposed as cosmo- + -naut. 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 "cosmonaut", not the corpus desk frequency band.

Same letter count

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

countable#52,244coalesced#52,224Chowdhury#52,219duplicity#52,285

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

Source: FrequencyWords open word-frequency list