noun

• (zoology, taxonomy) A designated paratype of a species (or lower-order taxon) that is the opposite sex of the holotype.
  "2007, Ivana Karanovic, Candoninae (Ostracoda) from the Pilbara Region in Western Australia, Koninklijke Brill, page 182, The allotype female has one T2 deformed (fig. 75D), while the other one is normally developed."
• (biochemistry) A genetically determined variant of the amino acid sequence of a protein.
  "2007, I. D. Walker, G. Winter, D. J. Worthington, Chapter 2: Structural Investigations of Peptides and Proteins: I: Primary Structure and Chemical Modification, R. C. Sheppard, Amino Acids, Peptides and Proteins, Volume 8, The Chemical Society, page 145, Until recently, different C-region allotypes were explained by allelic genes which each encoded a different but closely related protein sequence."
• (immunology) An immunoglobulin allotype; the allele of the antibody chains found in an individual.
  "The products of allelic forms of the same gene are known as allotypes. Allotypes are now known for all mouse heavy chains (Stall, 1995). There are no known serologically detectable allotypes of mouse κ chains."