ho·​mol·​o·​gy | \ hō-ˈmä-lə-jē How to pronounce homology (audio) , hə-\
plural homologies

Definition of homology

1 : a similarity often attributable to common origin
2a : likeness in structure between parts of different organisms (such as the wing of a bat and the human arm) due to evolutionary differentiation from a corresponding part in a common ancestor — compare analogy
b : correspondence in structure between a series of parts (such as vertebrae) in the same individual
3 : similarity of nucleotide or amino acid sequence (as in nucleic acids or proteins)
4 : a branch of the theory of topology concerned with partitioning space into geometric components (such as points, lines, and triangles) and with the study of the number and interrelationships of these components especially by the use of group theory

called also homology theory

— compare cohomology

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Did You Know?

The similarity of a structure or function of parts of different origins based on their descent from a common evolutionary ancestor is homology. Analogy, by contrast, is a functional similarity of structure that is based on mere similarity of use. For example, the forelimbs of humans, bats, and deer are homologous; the form of construction and the number of bones in each are almost identical and represent adaptive modifications of the forelimb structure of their shared ancestor. The wings of birds and insects, on the other hand, are merely analogous; both are used for flight, but they do not share a common ancestral origin.

Examples of homology in a Sentence

Recent Examples on the Web

The point is thus not to argue for absolute homology. Nancy K. Maclean, Slate Magazine, "America’s Brush With Fascism," 20 Mar. 2017

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'homology.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

First Known Use of homology

circa 1656, in the meaning defined at sense 1

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The first known use of homology was circa 1656

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ho·​mol·​o·​gy | \ hō-ˈmäl-ə-jē, hə- How to pronounce homology (audio) \
plural homologies

Medical Definition of homology

1a : likeness in structure between parts of different organisms due to evolutionary differentiation from the same or a corresponding part of a remote ancestor — compare analogy, homomorphy
b : correspondence in structure between different parts of the same individual
2a : the relation existing between chemical compounds in a series whose successive members have in composition a regular difference especially of one carbon and two hydrogen atoms CH2
b : the relation existing among elements in the same group of the periodic table
c : similarity of nucleotide or amino acid sequence (as in nucleic acids or proteins)

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More from Merriam-Webster on homology

Rhyming Dictionary: Words that rhyme with homology

Britannica English: Translation of homology for Arabic Speakers

Britannica.com: Encyclopedia article about homology

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