exo-

See also: exo

English

Etymology

Etymology tree

Proto-Indo-European *h₁éǵʰ

Proto-Indo-European *-s

Proto-Indo-European *h₁eǵʰs

Proto-Hellenic *eks

Ancient Greek ἐκ (ek)

Ancient Greek ἔξω (éxō)der.

English exo-

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

Pronunciation

• (General American) IPA^(key): /ɛksoʊ-/
• (Received Pronunciation) IPA^(key): /ɛksəʊ-/

Prefix

exo-

1. outside; external
   1. (astronomy) extrasolar; beyond the Solar System (our solar system)

      ‎exo- + ‎planet → ‎exoplanet

      ‎exo- + ‎biology → ‎exobiology

Synonyms

• (outside): out-, ex-, ecto-

Antonyms

• (antonym(s) of “outside”): in-, intra-, en-/em-/im-, end-/endo-/ento-

Derived terms

English terms prefixed with exo-

exoactive

exoamylase

exoamylasic

exoanthropic

exoantigen

exoarchaeology

exarchy

exoascus

exoasteroid

exoatmosphere

exoatmospheric

exobase

exobasidial

exobiological

exobiologist

exobiology

exobiotic

exocannibal

exocannibalism

exocanthion

exocapillary

exocarboxypeptidase

exocardiac

exocardial

exocarp

exocellobiohydrolase

exocellular

exocellulase

exocelomic

exocentered

exocentric

exocervical

exocervix

exocharmic

exochitinase

exochorion

exochorionic

exochromic

exochromosomal

exocoelom

exocoelomic

exocomet

exocometary

exocommunication

exocompound

exoconjugant

exoconsciousness

exoconsistency

exocortex

exocortical

exocranial

exocranially

exocuticle

exocuticular

exocyclic

exocytic

exocytoplasmic

exocytosis

exocytotoxic

exoderm

exodermal

exodeubiquitinase

exodeviation

exodigestion

exodomain

exodrift

exoearth

exoelectrogen

exoelectrogenesis

exoenergetic

exoenergic

exoenteric

exoenthalpic

exoenzymatic

exoenzyme

exoergonic

exoerythrocytic

exoethnonym

exaspidean

exocœlomic

exocon

exoergic

exometabolism

exophoria

exophorically

exopolysaccharide

exopolysaccharidic

exoproduct

exoface

exofacial

exofacially

exofocal

exogalactic

exogamous

exogamy

exogangue

exogastric

exogastrulate

exogen

exogenote

exogenesis

exogenetic

exogenic

exogenous

exogeny

exogeography

exogeology

exogeomorphology

exoglossic

exoglucanase

exoglycanase

exoglycohydrolase

exoglycosidase

exoglycosidic

exogonial

exohydrolase

exohydrolytic

exoinulinase

exo-isomer

exite

exokarst

exokernel

exokinase

exolabial

exolang

exolevanase

exolever

exolife

exolingual

exolipase

exolipid

exoloop

exolyase

exolysis

exolytic

exolytically

exomarker

exomeckelian

exomembrane

exometabolic

exometabolite

exometabolome

exometabolomic

exometabolomics

exomethylene

exomoon

exomorphism

exomorphological

exomorphology

exomusculature

exonarthex

exonorm

exonormative

exonucleated

exonucleation

exonucleolytic

exonucleotide

exonumia

exoccipital

exo-ocean

exonym

exonymy

exophthalmia

exosmosis

exosmotic

exoparasite

exopassive

exopathogen

exopause

exopectinase

exopeptidase

exoperidial

exoperidium

exoperitrophic

exophage

exophagic

exophagically

exophagy

exophasia

exophenotype

exophilic

exophily

exophobic

exophonic

exophony

exophosphatase

exophyte

exopinacocyte

exoplanar

exoplanet

exoplanetesimal

exoplasm

exoplasmic

exopod

exopodite

exopolitics

exopolygalacturonase

exopolymer

exopolymerase

exopolyphosphatase

• exosemantic

Related terms

• ecto-
• end- / endo-
• ex-
• extra-

Translations

Translations

• Georgian: ეგზო- (egzo-)
• Indonesian: ekso-
• Polish: egzo-
• Portuguese: exo- (pt)
• Russian: экзо- (ru) (ekzo-)
• Spanish: exo- (es)

Catalan

Etymology

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

Prefix

exo-

1. exo-

   Antonym: endo-

Derived terms

• Catalan terms prefixed with exo-

  exosquelet

  exògam

  exogàmia

  exònim

  exosfera

Related terms

• meso-

Czech

Etymology

Derived from Ancient Greek ἔξω (éxō, “outer, external”).

Pronunciation

• IPA^(key): [ɛɡzo ]

Prefix

exo-

1. exo-

   Antonym: endo-

Derived terms

Czech terms prefixed with exo-

exoplaneta

exoskelet

Further reading

• “exo-”, in Slovník spisovného jazyka českého (in Czech), 1960–1971, 1989
• exo- in Slovník afixů užívaných v češtině, 2017

French

Etymology

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

Prefix

exo-

1. exo-

   Antonym: endo-

Derived terms

• French terms prefixed with exo-

  exobiologie

  exobiologique

  exobiologiste

  exocarpe

  excroissance

  exogame

  exogéologie

  exogéomorphologie

  exoplanétologie

  exoscopie

  exosphère

  exosquelette

  exothermique

German

Etymology

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

Pronunciation

• Audio (Germany (Berlin)):

  (file)

Prefix

exo-

1. exo-

   Antonym: endo-

Derived terms

• German terms prefixed with exo-

  Exobiologie

  exogenetisch

  Exoplanet

  Exoskelett

  exozentrisch

Portuguese

Etymology

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

Pronunciation

• (Brazil) IPA^(key): /ˌe.zo/, /ˌɛ.zo/

• (Portugal) IPA^(key): /ˌe.zɔ/

Prefix

exo-

1. exo-

   Antonym: endo-

Derived terms

• Portuguese terms prefixed with exo-

  exosfera

  exoesqueleto

  exorreico

  exónimo

  exônimo

  exoplaneta

  exotérmico

Further reading

• “exo-”, in Dicionário Aulete Digital (in Portuguese), Rio de Janeiro: Lexikon Editora Digital, 2008–2026
• “exo-”, in Dicionário Priberam da Língua Portuguesa (in Portuguese), Lisbon: Priberam, 2008–2026

Spanish

Etymology

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

Prefix

exo-

1. exo-

Derived terms

Spanish terms prefixed with exo-

exoesqueleto

exógeno

exoluna

exónimo

exoplaneta

exotérmico

Further reading

• “exo-”, in Diccionario de la lengua española [Dictionary of the Spanish Language] (in Spanish), online version 23.8.1, Royal Spanish Academy [Spanish: Real Academia Española], 15 December 2025