Aegis, bouillon, chiton. Flautist, gyro, haute couture. Lackadaisical, mascarpone, peremptory. The English language is filled with words that stump the tongue with their tricky vowel pairings, consonants that seem neither hard nor soft, and rogue e’s that end up being anything but silent. Let’s face it, proper pronunciation is a trip.

Authors Ross and Kathryn Petras agree. They recently penned an entire book dedicated to the most commonly mispronounced words and their tangled histories. Titled You’re Probably Saying It Wrong, the small tome packs 150 of the most irritating words American-English speakers fail to get right.

From gourmet terms borrowed from French to colloquialisms born in the United States to the names of characters endemic to H. P. Lovecraft’s fictional universes (admit it, you’ve always wanted to know how to pronounce Cthulhu), they help readers master both the perplexing and perplexingly simple expressions that make ordering braised endive anxiety-inducing.

In honor of the new book, here is an excerpt from You’re Probably Saying It Wrong that provides eager readers with 12 explanations (assembled from dictionaries, linguistic accounts, surveys and more) to some of the most slippery words out there. Go forth and pronounce:

1. Acaí [ah-sigh-EE]

Brasil2 via Getty Images

What: A species of palm tree from the Amazon rain forest, best known for its health-giving reddish-purple berry.

How you pronounce it: It’s not ACK-ah-ee, it’s not ah-KAI, and it’s not ah-SIGH. It’s ah-sigh-EE, with a soft c and a stress on the last syllable.

For the spelling that tricks many English speakers, you can blame the early Portuguese explorers of Brazil, who saw indigenous rainforest people eating a strange and luscious palm tree berry that they called in their Tupi-Guarani language ïwaca’i (something that cries or expels water).

The Portuguese wrote this down as açaí, but in Portuguese the c comes with a squiggly cedilla at the bottom that makes the c sound soft, and there’s an accent on the i. The result is something very close to the original pronunciation. Since English doesn’t come equipped with softening cedillas and accents, the result is a very untasteful rendering of a very tasty fruit.

2. Chiaroscuro [kee-ahr-uh-SKYOOR-oh]

DEA / G. NIMATALLAH via Getty Images

What: In art, the treatment of light and shade, often in dramatic contrast.

How you pronounce it: Chiaroscuro looks odd, sounds odd, and just doesn’t crop up in everyday conversation since it basically refers to the artistic technique of balancing dark and light, the interplay of light and shadow. It came into English from the Italian and is still pronounced the Italian way, with chiaro (clear, bright) joined to oscuro, (obscure, dark). But to pronounce it correctly, it’s easier to think of four English words set in a row: “key arrow skew row.”

3. Flautist [FLOU-tist]

Sébastien Bonaimé via Getty Images

What: A person who plays the flute.

How you pronounce it: This is actually a trick shibboleth because the word flautist is indeed real and is pronounced the way you probably assume it is. But while the term is used widely in Britain, in the United States, flutist, pronounced as it is spelled (FLOO-tist), is preferred.

While you might think flutist is simply an American evolution of flautist, it isn’t. It’s actually the older of the two ― emerging in 1603, while flautist didn’t come around until 1860, first appearing in Nathaniel Hawthorne’s The Magic Faun. It’s possible Hawthorne chose flautist because the book was set in Italy, where flute is flauto and a flutist is a flautista. Flutist, on the other hand, is a direct offspring of the French flûtiste, which came from flûte. So flutist has the historical claim and the more direct genealogy. Even so, many Americans persist in thinking flautist sounds more correct, more sophisticated, and more musical.

4. GIF [jiff]

What: A computer graphic image; an acronym for Graphics Interchange Format.

How you pronounce it: Is it “giff” with a hard g or “jiff” with a soft one? Steve Wilhite says it’s “jiff” ... and he should know, since he developed GIFs for Compuserve. He chose to pronounce it that way because it sounded like Jif, the peanut butter brand. Employees would do a riff on Jif TV ads, saying, “Choosy developers choose GIF.”

But choosy people who didn’t develop the GIFs choose to say “giff” with a hard g. In fact, some dictionaries not only list both pronunciations, but place “giff” before “jiff.”

Wilhite hasn’t succumbed to pressure. When he got a lifetime achievement award back in 2013 at the Webby Awards, he gave a speech flatly rejecting “giff,” which was widely shared on the Internet. So if you do choose the hard g version, we advise you to keep your mouth shut around Mr. Wilhite.

5. Mischievous [MIS-chuh-vus]

Gallo Images - Peter Lillie via Getty Images

What: Wanting to or causing trouble, most often in a playful way.

How you pronounce it: We almost didn’t include this word because, although it often appears on lists of mispronounced words, we thought it was left over from the past. But once we really started listening, we discovered that many people still say it incorrectly. They all fell prey to the “let’s add an i in there and make it four syllables” syndrome, making the word “mis-CHEE-vee-us.”

To make things worse, this mispronunciation also lends itself to spelling errors. When people add the extra syllable, they often also add that i when they spell it, writing it “mischievious.” This mistake goes back many years, as far back as the sixteenth century, even though the word was initially spelled somewhat phonetically as the mid-fourteenth-century Anglo-Norman word meschevous.

6. Niche [neesh] or [nitch]

Andrew Geiger via Getty Images

What: A shallow recess in wall for a sculpture or other decorative object; a place or position suitable or appropriate for a person or thing; a market segment.

How you pronounce it: Here’s yet another French-derived shibboleth word with that pesky “che” ending that often throws people. In this case, instead of (wrongly) going for a super-faux-French sound and saying “ni-chay,” many people super-anglicize it and say “nitch.” This had been wrong until recently, as the preferred pronunciation was the one used since the seventeenth century ― a soft, long e “neesh” like the 14-century French word meaning recess for a dog, or kennel.

But as “nitch” has become a more commonly used pronunciation, it also has become more widely accepted. It’s even become the preferred pronunciation in some dictionaries.

Want to know six more words you’re mispronouncing?

Nathan Gelgud

Adapted from You’re Saying it Wrong, copyright © 2016 by Ross Petras and Kathryn Petras. Published by Ten Speed Press, an imprint of Penguin Random House LLC. The illustration comes courtesy of artist Nathan Gelgud and Signature.