exo-
/ɛksoʊ-/
"exo" is a 3-letter English headword indexed on PlainSpell.
The verdict
“exo-” is uncommon English (outside the top frequency list), classed as a prefix. The kind of spelling people second-guess.
- Unranked
- below top-frequency English
- 4
- letters
According to Wiktionary data (CC BY-SA, analyzed September 3, 2026) - outside; external
Corpus desk
Index EN-exo · exo- · English
exo- · unranked · 0 variants · 0 confusables
- FREQ-UNRANKED Unranked
- LEN-MID 4 letters
- VOW-2 2 vowels
- CONFUS-0 No pairs
- VAR-0 0 variants
- BOOK-THIN "E" 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.
| Property | Value |
|---|---|
| Headword | exo- |
| Language | English |
| Part of speech | Prefix |
| IPA | /ɛksoʊ-/ |
| Letters | 4 |
| Misspellings tracked | 0 |
| Confusable pairs | 0 |
| Source | Wiktionary (kaikki.org) |
Long-tail rank of “exo-” in English
Rare enough to double-check
exo- is uncommon English outside the top frequency list, classed as aprefix, transcribed /ɛksoʊ-/. Rarity is why readers land here mid-draft. 2 senses are on record.
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
- 1outside; external
- 2outside; external
Recorded use
Wiktionary examplesThese source excerpts show how exo- appears in context. They illustrate usage; the definition above remains the entry’s reference meaning.
exo- + planet → exoplanet
exo- + biology → exobiology
Etymology
From Ancient Greek ἔξω (éxō, “outer; external”).
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.