exo-

US/ɛksoʊ-/UK/ɛksəʊ-/

prefix

outside; external

“exo- + planet → exoplanet”

Similar
out-ex-ecto-
Opposite
in-intra-en-em-im-
OriginAncient Greek ἔξω (éxō) →
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Meanings

prefix
  1. outside; external
    1. astronomyextrasolar; beyond the Solar System (our solar system)

      exo- + planet → exoplanet

      1 more example

      exo- + biology → exobiology

Synonyms & antonyms

outside

Similar
out-ex-ecto-

antonym(s) of “outside”

Opposite
in-intra-en-em-im-end-endo-ento-
Also see
ecto-ex-out-

Origin

  1. Ancient Greekἐκ (ek)
  2. Ancient Greekἔξω (éxō)
  3. Englishexo-

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

More words from Ancient Greek

Full word history & related roots →

Translations

Greek εξω-
  • εξω- (exo-)Translations
Indonesian ekso-
  • ekso-Translations
Polish egzo-
  • egzo-Translations
Portuguese exo-
  • exo-Translations
Russian экзо-
  • экзо- (ekzo-)Translations
Spanish exo-
  • exo-Translations
Cite this entry
APA

exo-. (n.d.). In WatkinsX Dictionary. Retrieved November 3, 2026, from https://dictionary.watkinsx.com/word/exo-

MLA

“exo-.” WatkinsX Dictionary, https://dictionary.watkinsx.com/word/exo-. Accessed November 3, 2026.

Chicago

WatkinsX Dictionary, s.v. “exo-,” accessed November 3, 2026, https://dictionary.watkinsx.com/word/exo-.

Source: exo- on Wiktionary, CC BY-SA 4.0.