[ dif-thuh-roid, dip- ]
/ ˈdɪf θəˌrɔɪd, ˈdɪp- /

adjective Pathology.

resembling diphtheria, especially in the formation of a false membrane in the throat.


any bacterium, especially of the genus Corynebacterium, that resembles the diphtheria bacillus but does not produce diphtheria toxin.

Nearby words

  1. diphtheria, tetanus toxoids, and pertussis vaccine,
  2. diphtherial,
  3. diphtheric,
  4. diphtheritic,
  5. diphtheritic membrane,
  6. diphthong,
  7. diphthongia,
  8. diphthongize,
  9. diphycercal,
  10. diphyletic

Origin of diphtheroid

First recorded in 1860–65; diphther(ia) + -oid

Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

Medicine definitions for diphtheroids


[ dĭfthə-roid′ ]


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
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.