The Collaborative International Dictionary of English v.0.48:

Coincide \Co`in*cide"\, v. i. [imp. & p. p. Coincided; p. pr.
   & vb. n. Coinciding.] [L. co- + incidere to fall on; in +
   cadere to fall: cf. F. co["i]ncider. See Chance, n.]
   1. To occupy the same place in space, as two equal triangles,
      when placed one on the other.
      [1913 Webster]

            If the equator and the ecliptic had coincided, it
            would have rendered the annual revoluton of the
            earth useless.                        --Cheyne.
      [1913 Webster]

   2. To occur at the same time; to be contemporaneous; as, the
      fall of Granada coincided with the discovery of America.
      [1913 Webster]

   3. To correspond exactly; to agree; to concur; as, our aims
      coincide.
      [1913 Webster]

            The rules of right jugdment and of good
            ratiocination often coincide with each other.
                                                  --Watts.
      [1913 Webster]

WordNet (r) 3.0 (2006):

coincide
    v 1: go with, fall together [syn: coincide, co-occur,
         cooccur]
    2: happen simultaneously; "The two events coincided" [syn:
       concur, coincide]
    3: be the same; "our views on this matter coincided"

Moby Thesaurus II by Grady Ward, 1.0:

83 Moby Thesaurus words for "coincide":
   accompany, accord, agree, agree in opinion, agree with, answer to,
   assent, associate, assort with, be consistent, be in cahoots,
   be in phase, be in time, be of one, be uniform with, check, chime,
   chime in with, close with, coact, coadunate, coexist, coextend,
   cohere, collaborate, collude, combine, concert, concord, concur,
   conform, conform to, conform with, conjoin, connive, consist with,
   conspire, contemporize, cooperate, correspond, ditto, dovetail,
   echo, equal, fall in together, fall in with, fit together,
   go along with, go together, go with, hang together,
   happen together, harmonize, hit, hold together, interlock,
   intersect, isochronize, jibe, join, keep in step, keep pace with,
   line up, lock, match, meet, overlap, parallel, register,
   register with, respond to, side with, sing in chorus, sort with,
   square, square with, stand together, strike in with, synchronize,
   synergize, tally, time, unite