A golfer who hits a ball into the vicinity of others is beholden to yell “Fore!” to warn them to watch out for a sailing dimpled object. And that should be the only clue you need to figure out when the prefix “for” needs an “e.”

“Fore!” means “Look out in front of me!” And it really means “Look out before me!” “Fore” is a shortened form of “before.” So if it’s coming “before” something else, the prefix needs an “e.”

Pretty simple. Yet examples of a dropped “e”—or an added “e”—often come to the forefront.

Much of the time, it’s just a misspelling—for example, “forbode” instead of “forebode,” “forebid” instead of “forbid,” “forclose” instead of “foreclose,” or “foresake” instead of “forsake.”

But English also has a lot of words that differ only by that little “e,” and using the wrong one won’t trigger any spelling checker except a sharp brain. Things aren’t helped by the plain prefix “for,” which means “away, apart, off,” one direction of which could be “before.”

The opening of a book, for example, is the word that comes “before” the book, and so is a “foreword.” Yet it’s frequently spelled, even in many books, as “forward.” And “forward” is another word entirely, meaning, er, “toward the front.” OK, that’s one you’re just going to have to learn.

This one’s easier: “Forbear” means “to tolerate,” and has nothing to do with your “forebears,” your ancestors.” (“Forebearers” is incorrect, logical though it may sound.) One trick with this one: “Forebear” is always a noun. “Forbear” is a usually a verb; its noun form, “forbearance,” has no “e,” even if someone asks for your “forbearance” before the tolerance is required.

One of the trickiest pairs, though, is “forego” and “forgo.”

“Forego” is a verb meaning “to go before.” (There’s that “fore” again!) “Forgo” is a verb meaning “to do without.” For you Catholics out there, here’s a memory aid: During Lent, which “foregoes” Easter, you “forgo” something—the “e.”

Some dictionaries list “forego” as an alternative spelling to “forgo,” but if you’re smart, you’ll “forget” that.

Merrill Perlman managed copy desks across the newsroom at The New York Times, where she worked for 25 years.