Source : Webster's Revised Unabridged Dictionary (1913)

Coincidence \Co*in"ci*dence\, n. [Cf. F. co["i]ncidence.]
   1. The condition of occupying the same place in space; as,
      the coincidence of circles, surfaces, etc. --Bentley.

   2. The condition or fact of happening at the same time; as,
      the coincidence of the deaths of John Adams and Thomas
      Jefferson.

   3. Exact correspondence in nature, character, result,
      circumstances, etc.; concurrence; agreement.

            The very concurrence and coincidence of ao many
            evidences . . . carries a great weight. --Sir M.
                                                  Hale.

            Those who discourse . . . of the nature of truth . .
            . affirm a perfect coincidence between truth and
            goodness.                             --South.

Source : WordNet®

coincidence
     n 1: an event that might have been arranged although it was
          really accidental [syn: {happenstance}]
     2: the quality of occupying the same position or area in space;
        "he waited for the coincidence of the target and the cross
        hairs"
     3: the temporal property of two things happening at the same
        time; "the interval determining the coincidence gate is
        adjustable" [syn: {concurrence}, {conjunction}, {co-occurrence}]