[dif-thuh-roid, dip-]
  1. any bacterium, especially of the genus Corynebacterium, that resembles the diphtheria bacillus but does not produce diphtheria toxin.

Origin of diphtheroid

First recorded in 1860–65; diphther(ia) + -oid
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

diphtheroids in Medicine


  1. A local infection that resembles diphtheria, especially in the formation of a false membrane, but that is caused by a microorganism other than Corynebacterium diphtheriae.pseudodiphtheria
  2. Any of various microorganisms resembling Corynebacterium diphtheriae.
Related formsdiphthe•roid′ adj.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.