forego 有两个分身。分身1是 forgo 的变体 “do without”，分身2 “go before”，衍生出你提到的 foregoing “occurring before”。
The verb forgo, meaning "to abstain from, do without," has forego as an acceptable variant. Thus, one can forgo or forego dessert, though the spelling without the e is far more common and is preferred in most dictionaries. Forego also exists as a separate word meaning "to go before, either in place or time," as in The essential points have been laid out in the foregoing pages. The two words have historically been spelled differently because they incorporate different prefixes: The fore- of forego is the same prefix (meaning "in front, ahead, before") found in forefather, forehead, and foreword, while the for- of forgo is akin to the for- in forget, forlorn, and forsake and usually denotes loss or removal.