Webster’s Revised Unabridged Dictionary · 1913
Forgo
For·go′, v. t. [imp. Forwent; p. p. Forgone; p. pr. & vb. n. Forgoing.] [OE. forgan, forgon, forgoon, AS. forgān, prop., to go past, hence, to abstain from; pref. for- + gān to go; akin to G. vergehen to pass away, to transgress. See Go, v. i.] To pass by; to leave. See 1st Forego.
For sith [since] I shall forgoon my liberty At your request. Chaucer.
And four [days] since Florimell the court forwent. Spenser.
☞ This word in spelling has been confused with, and almost superseded by, forego to go before. Etymologically the form forgo is correct.