[in-ses-choo-uh s]
  1. involving incest.
  2. guilty of incest.
  3. being so close or intimate as to prevent proper functioning: an incestuous relationship between organized crime and government.

Origin of incestuous

1525–35; < Late Latin incestuōsus, equivalent to Latin incestu- stem of incestus incest + -ōsus -ous
Related formsin·ces·tu·ous·ly, adverbin·ces·tu·ous·ness, nounnon·in·ces·tu·ous, adjectivenon·in·ces·tu·ous·ly, adverbnon·in·ces·tu·ous·ness, nounun·in·ces·tu·ous, adjectiveun·in·ces·tu·ous·ly, adverb Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

British Dictionary definitions for incestuously


  1. relating to or involving incestan incestuous union
  2. guilty of incest
  3. obsolete resulting from incestan incestuous bastard
  4. resembling incest in excessive or claustrophobic intimacy
Derived Formsincestuously, adverbincestuousness, noun
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Word Origin and History for incestuously



1530s, from Latin incestuosus "incestuous," from incestus "unchaste" (see incest). Figurative use is from 1744. Related: Incestuously; incestuousness.

Online Etymology Dictionary, © 2010 Douglas Harper

incestuously in Medicine


  1. Of, involving, or suggestive of incest.
  2. Having committed incest.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.