In evolution, a successful organism can be said to have adapted or evolved. What about an organism that is clearly going to die out?

The example I have in mind is a parasite that kills its host.

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    what has your search revealed? – lbf Feb 16 '18 at 23:50
  • It's becoming extinct. – Hot Licks Feb 16 '18 at 23:58
  • The word I want won't be be too scientific or technical. It should be applicable to a parasitic person or business. 'Doomed' is not the right word but it captures the tragically wrong path taken by my subject. – Ken Feb 17 '18 at 1:06
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    I wish you'd said that in the first place, Ken! In fact it would be great if this site insisted on questions including details of 'what is it for?' A novel, advertising, essay, article - use such different language! And providing more or longer surrounding 'example text'. This context dramatically alters the answers that one would give! 💁A parasitic person is not going to need the same word as a parasitic plant, for example... – Jelila Feb 17 '18 at 2:26
  • What is 'a parasitic person in business', Ken? Do you mean, 'they destroy the company they work for?' In which case, how are they 'doomed'? Isn't the company the one that's 'doomed'? Please clarify. – Jelila Feb 17 '18 at 2:32

"ill-adapted" seems to be the term you're looking for.

  • The ill-adapted parasite species slays its host species and goes extinct; better-adapted parasites co-exist with their hosts, and the best-adapted will benefit their hosts at the species and even at the individual level. Overvirulence to the host decreases the parasite's chances of survival; a parasite can increase its chances by benefiting its host organism

  • Symposium on factors influencing host-parasitic relationships "It would appear, therefore, that in many instances the borderline between successful parasitism and disease is an exceedingly narrow one and it may be supposed that the changes required to upset the balance are not only of a very varied nature but sometimes need only be very slight in order to allow an ill-adapted parasite to multiply exceedingly and to cause disease.

ill-adapted means "unsuitable, inappropriate"

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  • wry, I like it.. – Ken Feb 17 '18 at 1:09

The premise of the biology of your question is a bit faulty, but I will leave that to Biology.SE.

I think the term you are looking for is either


in terms of a trait (I would prefer this usage in this context), or


in terms of the organism. For example, one could say

Ken birds are maladapted to the warming conditions in the arctic and are in danger of extinction.

The phrase

...the level of pathogen virulence is likely to be maladaptive not only for the host but also the pathogen.

fits the specific context you are referring to. (verbatim from Longdon, B., Hadfield, J. D., Day, J. P., Smith, S. C., McGonigle, J. E., Cogni, R., ... & Jiggins, F. M. (2015). The causes and consequences of changes in virulence following pathogen host shifts. PLoS Pathogens, 11(3), e1004728.)

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  • Welcome to English Language & Usage. This site prefers citations be done by hyperlinks , but you have done well with the answer. – J. Taylor Feb 17 '18 at 0:09

The organism is becoming (or "going") extinct.

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Evanesce, evanescing, evanescent

Gradually fade, disappear, or die out.

It means 'to pass out of sight, memory, or existence'.


  • the evanescent host is gradually dying
  • the evanescent star finally disappeared in the distance
  • Marilyn Monroe shone brightly as a candle, then evanesced
  • the evanescence of a shooting star makes it hard to catch



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