B lymphocyte also B-lym·pho·cyte (b??l?m?f?-s?t?)n. See B cell.American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.B cell n. 1. Also called B lymphocyte. a type of white blood cell that circulates in the blood and lymph and produces antibody upon encountering any antigen that has a molecular arrangement complementary to the antibody. 2. beta cell. [1970?75] Random House Kernerman Webster’s College Dictionary, © 2010 K Dictionaries Ltd. Copyright 2005, 1997, 1991 by Random House, Inc. All rights reserved.