- Immunology a genetic variant, esp. an antibody that acts as an antigen when introduced into the bodies of most other individuals of the same species
- Taxonomy an animal or plant specimen that shows physical characteristics, usually sexual ones, not shown in the holotype
- A biological specimen that is the opposite sex of a holotype.
- Immunology Any of the alleles in the constant region of a given subclass of immunoglobulin that are detectable as antigens by members of the same species having a different constant region.
allo- + -type