The Collaborative International Dictionary of English v.0.48:

Participate \Par*tic"i*pate\, a. [L. participatus, p. p. of
   participare to participate; pars, partis, part + capere to
   take. See Part, and Capacious.]
   Acting in common; participating. [R.] --Shak.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Participate \Par*tic"i*pate\, v. i. [imp. & p. p.
   Participated; p. pr. & vb. n. Participating.]
   To have a share in common with others; to take a part; to
   play a role; to partake; -- followed by in, formerly by of;
   as, to participate in a debate; to participate in a
   discussion. --Shak.
   [1913 Webster]

         So would he participate of their wants.  --Hayward.
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         Mine may come when men
         With angels may participate.             --Milton.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Participate \Par*tic"i*pate\, v. t.
   1. To partake of; to share in; to receive a part of. [R.]
      [1913 Webster]

            Fit to participate all rational delight. --Milton.
      [1913 Webster]

   2. To impart, or give, or share of. [Obs.] --Drayton.
      [1913 Webster]

WordNet (r) 3.0 (2006):

participate
    v 1: share in something [syn: participate, take part]
    2: become a participant; be involved in; "enter a race"; "enter
       an agreement"; "enter a drug treatment program"; "enter
       negotiations" [syn: enter, participate] [ant: chuck up
       the sponge, drop by the wayside, drop out, fall by the
       wayside, give up, quit, throw in, throw in the
       towel]

Moby Thesaurus II by Grady Ward, 1.0:

24 Moby Thesaurus words for "participate":
   be enfranchised, be implicated in, bear a hand, chip in,
   contribute, contribute to, engage in, enter into, go into,
   have suffrage, help decide, join, join in, make the scene, partake,
   partake in, partake of, participate in, pull an oar, share in,
   sit in, sit in on, take part in, vote