homology
noun
homology is a noun meaning “specifically, such relationship in the context of the geometry of perspective” (English Wiktionary, September 2026). It is spelled H-O-M-O-L-O-G-Y, and it appears about once in every 2 million words in written English (wordfreq, 2021 data). The plural of homology is homologies.
What does homology mean?
noun
- 1
specifically, such relationship in the context of the geometry of perspective.
- 2
An automorphism of the projective plane (representing a perspective projection) that leaves all the points of some straight line (the homology axis) fixed and maps all the lines through some single point (the homology centre) onto themselves.
If the homology centre lies on the homology axis, the homology is said to be singular or parabolic; otherwise, it is called non-singular or hyperbolic.
- 3
A general way of associating a sequence of algebraic objects, such as abelian groups or modules, to a sequence of topological spaces; also used attributively: see Usage notes below.
- 4
Given a chain complex {Gₙ} and its associated set of homomorphisms {Hₙ}, the rule which explains how each Hₙ maps Gₙ into the kernel of Gₙ₊₁.
Because of their connection with both homology and cohomology, chain complexes are an important topic of study in homological algebra.
- 5
The relationship, between elements, of being in the same group of the periodic table.
- 6
The relationship, between organic compounds, of being in the same homologous series.
- 7
The relationship, between characteristics or behaviours, of having a shared evolutionary or developmental origin;
- 8
specifically, a correspondence between structures in separate life forms having a common evolutionary origin, such as that between mammalian flippers and hands.
Source: English Wiktionary, dump of September 2, 2026 (CC BY-SA 4.0), through kaikki.org (Wiktextract).
How do you pronounce homology?
- US
Source: English Wiktionary, dump of September 2, 2026 (CC BY-SA 4.0), through kaikki.org (Wiktextract). Recordings: LL-Q1860_(eng)-Flame,_not_lame-homology.wav, Wikimedia Commons (author and licence on each file's page).
Forms of homology
- homologies plural
Source: English Wiktionary, dump of September 2, 2026 (CC BY-SA 4.0), through kaikki.org (Wiktextract).
How common is homology?
Homology appears about once in every 2 million words in written English, the 40,703rd most frequent word form in the list.
Source: written frequency: wordfreq 3.1 (a 2021 snapshot of Wikipedia, subtitles, news, books, web text and social media).
Homology in Spanish, French, German and Portuguese
Source: English Wiktionary, dump of September 2, 2026 (CC BY-SA 4.0), through kaikki.org (Wiktextract). Translations are Wiktionary's, by sense; a linked word has its own PlainSpell page.
Where does homology come from?
From Latin homologia, from Ancient Greek ὁμολογία (homología, “agreement, assent”); compare French homologie. By surface analysis, homo- + -logy. 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.
Source: English Wiktionary, dump of September 2, 2026 (CC BY-SA 4.0), through kaikki.org (Wiktextract).