1. Biology. a type specimen of the sex opposite to that of the holotype.
  2. Immunology. an antibody of a given class having certain molecular sites shared by only some members of a species and therefore acting as an antigen to other members of the same species.

Origin of allotype

1915–20; allo- + type; in immunological sense, probably back formation from allotypy < French allotypie, coined in 1956
Related formsal·lo·typ·ic [al-uh-tip-ik] /ˌæl əˈtɪp ɪk/, adjectiveal·lo·typ·i·cal·ly, adverbal·lo·typ·y [al-uh-tahy-pee] /ˈæl əˌtaɪ pi/, noun Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

British Dictionary definitions for allotype


  1. biology an additional type specimen selected because of differences from the original type specimen, such as opposite sex or morphological details
  2. immunol any of the variant forms of a particular immunoglobulin found among members of the same species
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

allotype in Medicine


  1. Any of the genetically determined variants in the constant region of a given subclass of immunoglobulin that is detectable as an antigen by members of the same species having a different constant region.
Related formsal′lo•typic (-tĭpĭk) adj.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.