exo-

/ɛksoʊ-/

//ɛksoʊ-// prefix

"exo" is a 3-letter English headword indexed on PlainSpell.

The verdict

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

Unranked
below top-frequency English
4
letters

According to Wiktionary data (CC BY-SA, analyzed May 6, 2026) - outside; external

Key facts for exo-
PropertyValue
Headwordexo-
LanguageEnglish
Part of speechPrefix
IPA/ɛksoʊ-/
Letters4
Misspellings tracked0
Confusable pairs0
SourceWiktionary (kaikki.org)

Where “exo-” sits in English frequency

exo- 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 exo- is 4 letters long, classified as a prefix, and transcribed in the International Phonetic Alphabet as /ɛksoʊ-/. It sits outside the most-frequent rank tiers, which is often why uncommon words generate more spelling variants per reader. Wiktionary records 2 distinct senses for this headword, so context determines which meaning a reader should apply.

exo- doesn't appear in our generated misspelling index, since its letter pattern doesn't lend itself to common typo substitutions. It is not paired with a close-neighbour confusable in our dataset, which typically means the spelling is too distinctive to be mistaken for another word.

Etymologically, the entry records: From Ancient Greek ἔξω (éxō, “outer; external”). The correct English form is exo-, spelled E-X-O--.

Definition

  1. 1
    outside; external
  2. 2
    outside; external

Etymology

From Ancient Greek ἔξω (éxō, “outer; external”).

Synonyms

Antonyms

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 "exo-"?
"exo-" is spelled E-X-O--. The IPA pronunciation is /ɛksoʊ-/.
What does "exo-" mean?
As a prefix, "exo-" means: outside; external
How do you pronounce "exo-"?
The IPA (International Phonetic Alphabet) transcription for "exo-" is /ɛksoʊ-/. 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 "exo-"?
From Ancient Greek ἔξω (éxō, “outer; external”). 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.

Using “exo-”

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

  • The one correct English spelling is E-X-O-- - every other letter order is a misspelling in standard orthography.
  • Say it as /ɛksoʊ-/ (IPA); tap the speaker on the pronunciation badge to hear it where audio exists.
  • 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