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 … the anthropologist is in the curious position of dealing with … striking homologies not necessarily due to historical contact …— Edward Sapir
2a evolutionary biology : correspondence or similarity in form or function between parts (such as the wing of a bat and the human arm) of different species resulting from modification of a trait possessed by a common ancestor : similarity of traits reflecting common descent and ancestry — compare analogy, homoplasy
b anatomy : 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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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 Toward this end, the book explains the important difference between analogy and homology. David P. Barash, WSJ, 6 May 2022 Quanta also explored the origins of topology itself with a column in January and an explainer devoted to the related subject of homology. Quanta Magazine, 23 Dec. 2021 After all, the Yunnan bat virus with the 96 percent homology to the Wuhan human strain was found approximately 1,000 miles away. Maryn Mckenna, Wired, 2 Dec. 2020 In the late 1980s, a mathematician named Andreas Floer developed a theory called Floer homology, a powerful framework that is now the primary way mathematicians investigate symplectic phenomena. Quanta Magazine, 29 July 2020 Follow tradition, of course, and enforce the homology down the generations. Jason Kehe, Wired, 13 Jan. 2020 Human studies need more ecologically valid stimuli and better behavioral assays, in particular ones that do not rely on verbal report and that can be argued to have some homology to the behavioral assays used in animal studies. Dean Mobbs, Scientific American, 20 Sep. 2019 At the same time, other necessary characteristics of these homology 3-spheres require beta to be even. Quanta Magazine, 13 Jan. 2015 The Big Break Floer homology is a mathematical toolkit developed in the 1980s by Andreas Floer, a brilliant young German mathematician who died in 1991 at the age of 34. Quanta Magazine, 13 Jan. 2015 See More

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.

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First Known Use of homology

circa 1656, in the meaning defined at sense 1

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Time Traveler for homology

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The first known use of homology was circa 1656

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Dictionary Entries Near homology



homolosine projection

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Statistics for homology

Last Updated

18 May 2022

Cite this Entry

“Homology.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/homology. Accessed 20 May. 2022.

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More Definitions for homology


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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