bed·bug also bed bug (b?d?b?g?)n. Any of several small wingless parasitic insects of the family Cimicidae, especially Cimex lectularius, which infests dwellings and bedding and feeds on human blood. Also called regionally chinch.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.