[op-er-too-nis-tik, -tyoo-]
  1. adhering to a policy of opportunism; practicing opportunism.
  2. Pathology.
    1. (of a microorganism) causing disease only under certain conditions, as when a person's immune system is impaired.
    2. (of a disease or infection) caused by such an organism: Pneumocystis pneumonia is an opportunistic disease that often strikes victims of AIDS.

Origin of opportunistic

First recorded in 1890–95; opportunist + -ic
Related formsop·por·tun·is·ti·cal·ly, adverbun·op·por·tun·is·tic, adjective
Can be confusedopportune opportunistic
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

Examples from the Web for opportunistically

Contemporary Examples of opportunistically

  • We now have more capital than we anticipated, [which will] allow us to opportunistically build what we have not been able to do.

    The Daily Beast logo
    A $125 Billion (Taxpayer) Gamble

    William D. Cohan

    October 20, 2008

Historical Examples of opportunistically

British Dictionary definitions for opportunistically


  1. of or characterized by opportunism
  2. med (of an infection) caused by any microorganism that is harmless to a healthy person but debilitates a person whose immune system has been weakened by disease or drug treatment
Derived Formsopportunistically, adverb
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 opportunistically



1889, see opportunist + -ic. Related: Opportunistically.

Online Etymology Dictionary, © 2010 Douglas Harper

opportunistically in Medicine


  1. Of or relating to an organism capable of causing disease only in a host whose resistance is lowered.
  2. Of or relating to a disease caused by an opportunistic organism.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.