[ huh-mol-uh-guhs, hoh- ]
/ həˈmɒl ə gəs, hoʊ- /
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having the same or a similar relation; corresponding, as in relative position or structure.
corresponding in structure and in origin, but not necessarily in function: The wing of a bird and the foreleg of a horse are homologous.
having the same alleles or genes in the same order of arrangement: homologous chromosomes.
Chemistry. of the same chemical type, but differing by a fixed increment of an atom or a constant group of atoms: Methyl and ethyl alcohols are homologous.
Immunology. pertaining to an antigen and its specific antibody.
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Origin of homologous

1650–60; <Medieval Latin homologus<Greek homólogos agreeing, equivalent to homo-homo- + -logos proportional, equivalent to log- (stem of lógos proportion; see logos) + -os-ous


non·ho·mol·o·gous, adjectiveun·ho·mol·o·gous, adjective
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2023


What does homologous mean?

Homologous is used to describe multiple things that are the same or similar, especially in structure or origin.

In science, homologous is most often used in the phrase homologous structures, which refers to body parts of animals that have a similar structure or origin, as in The arms of humans and the limbs of cats are homologous structures—the layout of the bones is very similar.  

Homologous structures may have different functions. For example, a human arm and a bat’s wing are considered homologous structures because they have the same bone structure, even though they obviously have different functions.

In biology, the presence of similarities like this is known as homology.

Homologous structures are the opposite of analogous structures, which refers to body parts that serve similar functions but have different structures or origins. For example, both birds and wasps have wings, but their wings have different appearances and consist of different parts and evolved from different origins.

Example: A horse’s leg and a whale’s flipper are homologous structures that evolved from the same origin.

Where does homologous come from?

The first records of homologous come from the 1650s. It ultimately comes from the Greek homólogos, which means “agreeing.” Homólogos is made from homo-, meaning “same,” and -logos (here meaning “proportional”).

Homologous structures are studied in the scientific fields of biology and anatomy. They are one of the many pieces of evidence that supports the theory of evolution. Homologous structures suggest that many animals evolved from a common ancestor and their similar skeletons and body parts evolved over time to adapt to their specific habitats.

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What are some other forms related to homologous?

  • nonhomologous (adjective)
  • unhomologous (adjective)

What are some synonyms for homologous?

What are some words that share a root or word element with homologous

What are some words that often get used in discussing homologous?


What are some words homologous may be commonly confused with?

How is homologous used in real life?

Homologous is a scientific term. It’s especially used in anthropology and biology.



Try using homologous!

Is homologous used correctly in the following sentence?

The arms of starfish and the arms of humans are homologous structures that have completely different parts and origins.

How to use homologous in a sentence

British Dictionary definitions for homologous


homological (ˌhəʊməˈlɒdʒɪkəl, ˌhɒm-) or homologic

/ (həʊˈmɒləɡəs, hɒ-) /

having a related or similar position, structure, etc
chem (of a series of organic compounds) having similar characteristics and structure but differing by a number of CH 2 groups
  1. (of two or more tissues) identical in structure
  2. (of a vaccine) prepared from the infecting microorganism
biology (of organs and parts) having the same evolutionary origin but different functionsthe wing of a bat and the paddle of a whale are homologous Compare analogous (def. 2)
maths (of elements) playing a similar role in distinct figures or functions

Derived forms of homologous

homologically, adverb
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

Scientific definitions for homologous

[ hə-mŏlə-gəs ]

Similar in structure and evolutionary origin but having different functions, as a human's arm and a seal's flipper.
Being one of a pair of chromosomes, one from the female parent and one from the male parent, that have genes for the same traits in the same positions. Genes on homologous chromosomes may not have the same form, however. For example, one chromosome in a pair of homologous chromosomes may contain a gene for brown eyes, and the other a gene for blue eyes. Human females have 23 pairs of homologous chromosomes (including the two X chromosomes), while human males have 22 because the Y chromosome is not paired.
Belonging to or being a series of organic compounds, each successive member of which differs from the preceding member by a constant increment, especially by an added CH2 group. The alkanes (methane, ethane, propane, and others) are a homologous series of compounds.
Involving organisms of the same species, as in grafted body tissues.
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.