Day 6·QUIZ

Illusion or allusion? Let these word nerds help save you from these common language mistakes

Brother and sister Ross and Kathy Petras, authors of That Doesn't Mean What You Think It Means, are here to help you understand the difference between 'alright' and 'all right.' Take our quiz and find out how you do.

Take our quiz and find out how your language skills stack up

Kathryn, left, and Ross Petras are the authors of That Doesn't Mean What You Think It Means. (Submitted by Kathryn Petras, Penguin Random House, Submitted by Ross Petras)

This was originally published on Oct. 3, 2018.

Do you know the difference between "less" and "fewer"? What about "nauseous" and "nauseated"? 

The English language is full of potential pitfalls. But Kathy and Ross Petras have your back.

In their new book That Doesn't Mean What You Think It Means, the siblings teamed up to set the record straight on 150 of the most commonly misused words in the English language.

And they uncovered some pretty strange errors — including the time an employee tried to compliment his boss by telling him he was the "penultimate leader."

"It means 'second to last,'" Ross told Day 6. "It's not very high praise."

Click 'Listen' above to hear the Petras siblings clear the air on everything from pristine swamps to penumbras — and then, if you dare, take our quiz to see how your grasp of the English language stacks up.