The Collaborative International Dictionary of English v.0.48:

Coincident \Co*in"ci*dent\ (k[-o]*[i^]n"s[i^]*dent), a. [Cf. F.
   co["i]ncident.]
   Having coincidence; occupying the same place;
   contemporaneous; concurrent; -- followed by with.
   [1913 Webster]

         Christianity teaches nothing but what is perfectly
         suitable to, and coincident with, the ruling principles
         of a virtuous and well-inclined man.     --South.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Coincident \Co*in"ci*dent\, n.
   One of two or more coincident events; a coincidence. [R.]
   "Coincidents and accidents." --Froude.
   [1913 Webster]

WordNet (r) 3.0 (2006):

coincident
    adj 1: occurring or operating at the same time; "a series of
           coincident events" [syn: coincident, coincidental,
           coinciding, concurrent, co-occurrent,
           cooccurring, simultaneous]
    2: matching point for point; "coincident circles"