forego (v.) Look up forego at
"to go before," Old English foregan "to go before," from fore- + go (v.). Related: Foregoer, foregoing; foregone. Similar formation in Dutch voorgaan, German vorgehen, Danish foregaa.

Phrase foregone conclusion echoes "Othello" [III.iii], but Shakespeare's sense was not necessarily the main modern one of "a decision already formed before the case is argued." Othello says it of Cassio's dream, and it is clear from the context that Othello means Cassio actually has been in bed with Desdemona before he allegedly dreamed it (the suspicion Iago is nourishing in him).