Any of several immunologically distinct, genetically determined classes of human blood that are based on the presence or absence of certain antigens and are clinically identified by characteristic agglutination reactions. Also called blood type.
American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.