[huh-mol-uh-jee, hoh-]
noun, plural ho·mol·o·gies.
  1. the state of being homologous; homologous relation or correspondence.
  2. Biology.
    1. a fundamental similarity based on common descent.
    2. a structural similarity of two segments of one animal based on a common developmental origin.
  3. Chemistry. the similarity of organic compounds of a series in which each member differs from its adjacent compounds by a fixed increment, as by CH2.
  4. Mathematics. a classification of figures according to certain topological properties.

Origin of homology

1650–60; < Greek homología agreement, equivalent to homólog(os) homologous + -ia -y3
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

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Historical Examples of homologies

British Dictionary definitions for homologies


noun plural -gies
  1. the condition of being homologous
  2. chem the similarities in chemical behaviour shown by members of a homologous series
  3. zoology the measurable likenesses between animals, as used in grouping them according to the theory of cladistics

Word Origin for homology

C17: from Greek homologia agreement, from homologos agreeing; see homologate
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

homologies in Science


  1. A homologous relationship or correspondence.
  2. The relation of the chemical elements of a periodic family or group.
  3. The relation of the organic compounds forming a homologous series.
  4. A topological classification of configurations into distinct types that imposes an algebraic structure or hierarchy on families of geometric figures.
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.