What does homologue mean?
A homologue is something that corresponds to another in structure, function, or origin. Its best-known use is in biology, where it describes an anatomical structure in one species that corresponds to a structure in another because both were inherited from a common ancestor. For example, a human arm and a bat wing are homologues even though they perform different functions. Homologues can also be genes, molecules, or other biological components. The central distinction is between homology and analogy: homologues owe their correspondence to shared ancestry, whereas analogous structures perform similar functions without necessarily having the same evolutionary origin. Because of this precision, “homologue” is especially useful in anatomy, genetics, evolutionary biology, and related technical writing, although “counterpart” is more common in general speech.
nounA structure, organ, molecule, or other entity that corresponds to another in form or function, especially one in a different species. The term is most often used in biology to describe structures inherited from a common ancestor.
- A corresponding organ or structure in a different species, especially when inherited from a common ancestor.
- More generally, a molecule, part, or other entity that corresponds to another in structure, function, or evolutionary origin.
"The forelimb of a human is a homologue of the wing of a bat."
"Researchers compared the mouse gene with its homologue in humans."
"The enlarged eyes of a horse are homologues of the eyes of other mammals, despite their different proportions."
The plural adds -s to the ending -gue, as in “several corresponding homologues.”
"The researchers compared homologues of the gene from several different species."
A bat's wing and your arm are different in everyday use, but anatomically they are homologues: inherited from a shared ancestral limb.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Where does homologue come from?
The word was formed in the 19th century from Greek homos, meaning “same,” combined with the element -logos, meaning “word,” “account,” or “relation.” Its immediate source is the Latinized form homologus, used for something corresponding or similar. The underlying Greek roots express the central idea of correspondence, while the biological sense developed from the comparison of corresponding structures across species.
Related word forms
How homologue is actually used
The word is primarily a technical term in biology, but it is also used in chemistry, comparative anatomy, and other fields. In everyday discussion, its near-synonym “counterpart” is usually more accessible.
Easily confused with homologue
A homologue is determined chiefly by shared evolutionary origin, whereas an analogue performs a similar function without necessarily sharing the same evolutionary origin.
The two terms are closely related, but a homologue usually refers to a corresponding biological structure, while a homolog more generally denotes something corresponding in origin, structure, or function.