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         almost superseded by, forego to go before.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]

WordNet (r) 3.0 (2006):

forgoing
    n 1: the act of renouncing; sacrificing or giving up or
         surrendering (a possession or right or title or privilege
         etc.) [syn: renunciation, forgoing, forswearing]