The Collaborative International Dictionary of English v.0.48:

Incident \In"ci*dent\, a. [L. incidens, -entis, p. pr. & of
   incidere to fall into or upon; pref. in- in, on + cadere to
   fall: cf. F. incident. See Cadence.]
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   1. Falling or striking upon, as a ray of light upon a
      reflecting surface.
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   2. Coming or happening accidentally; not in the usual course
      of things; not in connection with the main design; not
      according to expectation; casual; fortuitous.
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            As the ordinary course of common affairs is disposed
            of by general laws, so likewise men's rarer incident
            necessities and utilities should be with special
            equity considered.                    --Hooker.
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   3. Liable to happen; apt to occur; befalling; hence,
      naturally happening or appertaining.
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            All chances incident to man's frail life. --Milton.
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            The studies incident to his profession. --Milward.
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   4. (Law) Dependent upon, or appertaining to, another thing,
      called the principal.
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   Incident proposition (Logic), a proposition subordinate to
      another, and introduced by who, which, whose, whom, etc.;
      as, Julius, whose surname was C[ae]sar, overcame Pompey.
      --I. Watts.
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