What does heterologous mean?
Heterologous is a technical adjective meaning unlike in kind or not homologous. In comparative biology, it describes structures that lack the same anatomical correspondence or shared evolutionary relationship, distinguishing them from true homologues. In immunology, the term is narrower: a heterologous antigen, antibody, antiserum, or immune response comes from, or is directed against, a different species. In transplantation, heterologous tissue is taken from another species. These uses share the sense of a difference in origin, but the scientific context determines how far apart the things are. The word is specialized, appearing mainly in research writing rather than everyday speech. It is especially worth knowing alongside homologous: although the two may resemble one another, they are not evolutionary counterparts. Its Greek roots reinforce the contrast: heteros means “other,” and the word belongs to a family ending in -logous that also includes homologous and analogous.
adjectiveOf or relating to things that are unlike in type, origin, or correspondence; not homologous. In immunology and transplantation, specifically, involving something from a different species or an antigenically distinct source.
- Different in type, origin, or anatomical correspondence; not homologous.
- In immunology, originating in or involving a different species, especially an antigen, antibody, or antiserum.
- In transplantation, involving tissue or an organ obtained from a different species.
"The antiserum was heterologous, having been raised in a different species."
"Evolutionary biologists identified the paired structures as heterologous rather than homologous."
"The tissue was rejected because the graft was heterologous."
Heterologous is the scientific label for something that may look or function similarly without being a true counterpart.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Where does heterologous come from?
The word combines Greek heteros, meaning “other,” with the combining element -logous, which continues Greek logos, meaning “word,” “account,” or “proportion.” In biology and related sciences, it developed to mean “different in kind or correspondence” and, especially in immunology, “from another species.” Analogous, homologous, and isologous share the -logous formation but use different first elements.
How heterologous is actually used
The word is formal and highly technical, occurring chiefly in biology, immunology, medicine, and related research. In immunology, it is commonly contrasted with homologous; in transplantation, it also differs from autologous, which means derived from the same individual.
Easily confused with heterologous
Homologous means corresponding through shared ancestry or, in immunology, associated with the same species or source, whereas heterologous means not corresponding or originating from a different species.
Heterogeneous means composed of varied or dissimilar elements, while heterologous more specifically means not homologous or, in biological contexts, derived from a different species.