A congener (from Latin roots meaning "born together" or "within the same race or kind") has several different meanings depending on the field in which it is used. Colloquially, it is used to mean a person or thing like another in character or action.
In biology, congeners are organisms within the same genus. Congeners within the same geographical region can compete with one another so many adaptations can be observed that mitigate this pressure on populations
- There are 209 congeners of polychlorinated biphenyls (PCB) as well as 209 congeners of polybrominated diphenyl ethers (PBDE).
- Congeners of oleic acids can modify cell membrane behavior protecting against tumors or having effects on blood pressure.
In the alcoholic beverage industry, congener refers to impurities produced during fermentation or to metals such as zinc, added to certain sweet liqueurs in order to enhance flavor. Congeners are responsible for most of the taste, aroma, and color of alcoholic beverages. It has been suggested that these substances also contribute to the symptoms of a hangover, although the more likely cause is a more complicated mix of ethanol, dehydration, and various other factors (see hangover for a more complete list).
In genetics, congenic organisms are organisms with very similar genomes, except for a small fraction. For example, recombinant congenic mice strains are produced in laboratories as a tool to study genetic disease.