The Collaborative International Dictionary of English v.0.48:

Forgo \For*go"\, v. t. [imp. Forwent; p. p. Forgone; p. pr.
   & vb. n. Forgoing.] [OE. forgan, forgon, forgoon, AS.
   forg[=a]n, prop., to go past, hence, to abstain from; pref.
   for- + g[=a]n to go; akin to G. vergehen to pass away, to
   transgress. See Go, v. i.]
   1. To pass by; to leave. See 1st Forego.
      [1913 Webster]

            For sith [since] I shall forgoon my liberty
            At your request.                      --Chaucer.
      [1913 Webster]

            And four [days] since Florimell the court forwent.
                                                  --Spenser.
      [1913 Webster]

   2. to abstain from; to do without; to refrain from; to
      renounce; -- said of a thing already enjoyed, or of one
      within reach, or anticipated. See 1st forego, 2.
      [PJC]

   Note: This word in spelling has been confused with, and
         almost superseded by, forego to go before.
         Etymologically the form forgo is correct.
         [1913 Webster]

Moby Thesaurus II by Grady Ward, 1.0:

21 Moby Thesaurus words for "forgone":
   abandoned, abjured, ceded, dispensed with, disposed of,
   foreordained, forsworn, predecided, predestinate, predestined,
   predetermined, preordained, recanted, released, relinquished,
   renounced, retracted, sacrificed, surrendered, waived, yielded