Survival of the fittest

from WordNet (r) 3.0 (2006)

survival of the fittest
    n 1: a natural process resulting in the evolution of organisms
         best adapted to the environment [syn: {survival}, {survival
         of the fittest}, {natural selection}, {selection}]

from The Collaborative International Dictionary of English v.0.48

Survival \Sur*viv"al\, n. [From {Survive}.]
   1. A living or continuing longer than, or beyond the
      existence of, another person, thing, or event; an
      outliving.
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   2. (Arhaeol. & Ethnol.) Any habit, usage, or belief,
      remaining from ancient times, the origin of which is often
      unknown, or imperfectly known.
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            The close bearing of the doctrine of survival on the
            study of manners and customs.         --Tylor.
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   {Survival of the fittest}. (Biol.) See {Natural selection},
      under {Natural}.
      [1913 Webster] Survivance