It’s time for the next installment in our list of commonly confused words. This time I’ve included several that are both commonly misused and commonly requested as subjects for me to cover. You can check out earlier portions of the list at Insider 3-21-12, Insider 9-20-2011, and Insider 7-12-2011.

border/boarder

A “border” is the edge of something, such as a tunic, a parchment, or a territory. A “boarder,” however, is someone who pays for a room and meals (thus the term “room and board”).

Trick of Remembering: A clear border between nations usually contributes to order in the area (unless it’s contested, of course; in that case, it usually brings orders instead).

flounder/founder

You may know a “flounder” is a fish, while a “founder” is a person who establishes something (like a seafood restaurant), but the words have other meanings. At first glance those other meanings might seem relatively similar, as they both have to do with failure. The difference is significant, though: To “flounder” is to move clumsily or to make mistakes, while to “founder” is to fail outright. In the context of a ship, founder means “to take on water and sink.”

It may help to know that “founder” comes from the Latin word “fundus” (also related to “fundamental”), which means “bottom.” No way out; final.

forbear/forebear

Despite how much they look alike, these two words aren’t related in meaning at all. To “forbear” from something is to refrain from it, while “forebears” are ancestors: those who bore—or sired—children in previous generations of the family tree. (“Forebearers” is another word for ancestors and is equally acceptable. It’s simply a few hundred years newer.)

Trick of Remembering: The key here is the more common modern word “before,” which originally meant “by the fore,” or “in front.” (You see its influence in words like “forehead,” “forecast,” and “forerunner.”) Be sure to retain the “e” at the end of the word to keep its meaning. If, on the other hand, you mean to refrain from something, refrain from using that “e” in “forbear.”

their vs. they’re vs. there

This set of words shows up on many lists like this one, and for good reason: confusing them is both incredibly common and incredibly annoying to folks who understand the difference. Getting these straight is one thing you can do that’s guaranteed to improve others’ perception of you. (You can debate the fairness of such judgments elsewhere; for me, seeing them misused is a synesthethic experience akin to discovering forgotten leftovers creating a new habitat in the back of the refrigerator.)

“Their” is the third-person plural possessive pronoun. That just means it’s short for “belonging to them.”

“They’re” is the contraction of “they” and “are.” (Remember, the rule for contractions is that the apostrophe stands in for the missing letter or letters. In this case that’s the “a” in “are.”) It keeps us moving along at a good clip.

“There” is the oddball in this trio, as it has nothing to do with “them” or “they”; it just happens to sound like words that do. It refers to a specific location, position, or time. It can also be used to introduce part of a sentence whose grammatical subject is unclear.

Trick of Remembering: Do you want a word for location? Then think “Where’s the word I want? It’s there.” Can you substitute “they are”? Then you want they’re.