The Collaborative International Dictionary of English v.0.48:

Entity \En"ti*ty\, n.; pl. Entities. [LL. entitas, fr. L. ens,
   entis, thing, prop. p. pr. of esse to be: cf. F. entit['e].
   See Essence, Is.]
   A real being, whether in thought (as an ideal conception) or
   in fact; being; essence; existence.
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         Self-subsisting entities, such as our own personality.
                                                  --Shairp.
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         Fortune is no real entity, . . . but a mere relative
         signification.                           --Bentley.
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