Etymograph

English

homology

Homology comes from Ancient Greek ὁμολογία ‘agreement, assent’, from ὁμός ‘same, common, joint’, and ultimately from Proto-Indo-European *sem- ‘together, one’.

  1. Proto-Indo-Europeanc. 4500–2500 BCE*sem-1‘together, one’reconstructed
  2. Proto-Indo-Europeanc. 4500–2500 BCE*somHós2‘same, alike’reconstructed
  3. Proto-Hellenicc. 2200–1600 BCE*homós2reconstructed
  4. Ancient Greekc. 800–300 BCEὁμός3‘same, common, joint’
  5. Ancient Greekc. 800–300 BCEὁμόλογος4‘in agreement, of one mind’
  6. Ancient Greekc. 800–300 BCEὁμολογία5homología‘agreement, assent’
  7. Latinc. 75 BCE–200 CEhomologia5
  8. Englishearliest quotation 2000homology5

attested reconstructed ? uncertain or disputed deepest recorded ancestor

  1. 1 Wiktionary, Proto-Indo-European *somHós
  2. 2 Wiktionary, Ancient Greek ὁμός
  3. 3 Wiktionary, Ancient Greek ὁμόλογος
  4. 4 Wiktionary, Ancient Greek ὁμολογία
  5. 5 Wiktionary, English homology
  6. Earliest quotation in Wiktionary’s entry: 2000, Sibe Mardešić, Strong Shape and Homology: “One encounters a similar situation in homology theory. Beside…”.

Lineage

  1. Proto-Indo-Europeanc. 4500–2500 BCE*sem-Wiktionary, Proto-Indo-European *somHós‘together, one’reconstructed
  2. Proto-Indo-Europeanc. 4500–2500 BCE*somHósWiktionary, Ancient Greek ὁμός‘same, alike’reconstructed
  3. Proto-Hellenicc. 2200–1600 BCE*homósWiktionary, Ancient Greek ὁμόςreconstructed
  4. Ancient Greekc. 800–300 BCEὁμόςWiktionary, Ancient Greek ὁμόλογος‘same, common, joint’
  5. Ancient Greekc. 800–300 BCEὁμόλογοςWiktionary, Ancient Greek ὁμολογία‘in agreement, of one mind’
  6. Ancient Greekc. 800–300 BCEὁμολογίαWiktionary, English homologyhomología‘agreement, assent’
  7. Latinc. 75 BCE–200 CEhomologiaWiktionary, English homology
  8. Englishearliest quotation 2000homologyWiktionary, English homology. Earliest quotation in Wiktionary’s entry: 2000, Sibe Mardešić, Strong Shape and Homology: “One encounters a similar situation in homology theory. Beside…”

Equivalent to homo- + -logy

Proto-Indo-European *sem- ‘one, whole’

Proto-Indo-European *somHós ‘same, alike’

Proto-Hellenic *homós

Ancient Greek ὁμός ‘same’

English homo-

The story

In topology, first used by French polymath Henri Poincaré, in the sense (close to what is now called a bordism) of a relation between manifolds mapped into a reference manifold: that is, the property of such manifolds that they form the boundary of a higher-dimensional manifold inside the reference manifold. Poincaré's version was eventually replaced by the more general singular homology, which is what mathematicians now mean by homology.

Full etymology on Wiktionary

Linked words

through Proto-Indo-European *sem- ‘together, one’

some, single, similar, seem, simple, simply, soft, sam, simulation, sincerely, singular, resemble, assemble, resemblance, simultaneous, simulate, sincerity, anomaly, semblance, assimilate, synapse, insincere, hyphen, anomalous, simile, simulacrum, sempre, synchronise, 47 more

through Proto-Indo-European *somHós ‘same, alike’

same, 11 more

through Ancient Greek ὁμός ‘same, common, joint’

homeopathic, 10 more

Today it means

noun specifically, such relationship in the context of the geometry of perspective.

Sources

Sources: Wiktionary, “homology”; the older steps come from the Wiktionary entries for Proto-Indo-European *somHós, Ancient Greek ὁμός, Ancient Greek ὁμόλογος, Ancient Greek ὁμολογία. By Wiktionary contributors, CC BY-SA 4.0, via kaikki.org (dump of Oct 3 2026); text adapted and restructured. Language periods are conventional ranges, not dates for this word. License.

Etymograph / Proto-Indo-European *sem- / homology

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