14 crossword puzzle clues you can only solve if you're really smart

Harry Engels/Getty ImagesGrab a pencil and get ready for some wordplay.

Crossword Puzzle Day is recognised every year on December 21. On that day in 1913, British-born journalist Arthur Wynne published the first modern crossword puzzle – a diamond-shaped word game – in the Sunday edition of the now-defunct New York World.

In honour of Crossword Puzzle Day this year, INSIDER spoke with professional puzzlemaker Brendan Emmett Quigley, whose puzzles have been featured in The New York Times, The Washington Post, The Wall Street Journal, and more, since 1996. He also posts new puzzles every week on his website, categorized into three difficulty levels: easy, medium, and hard.

According to Quigley, hard crossword puzzles often test your mind’s ability to be “elastic,” to manipulate or “play around with the English language.” Compared to easier clues that are more straightforward, difficult clues “ask a little more from the solver” – even when the answers are the same.

For example, it’s a lot easier to solve “meat for breakfast” than “strips in a club.” The answer to both clues is “bacon,” but the latter has a “surface reading that sounds nothing like what you’re actually asking for,” Quigley explained. Another classic example is “drops on the ground,” which prompts solvers to think of a verb when the answer is actually a noun: “dew.”

Drawing from Quigley’s archive of hard puzzles, we rounded up a list of difficult crossword puzzle clues that will stimulate your brain, test your vocabulary, and challenge you to think outside the box.

Check them out below, but scroll down slowly as we’ve included the answers below each picture.

CLUE: They come in last (3 letters)

Daniel Kalisz/Getty ImagesYour mind probably jumps to a competition — but think again.

Answer: XYZ

Explanation: “X,” “Y,” and “Z” are the last letters of the English alphabet.

See the full puzzle here.

CLUE: Pictures of Yosemite? (4 letters)

Answer: Cels

Explanation: Yosemite Sam is an animated cartoon character. A cel, or celluloid, is a transparent sheet on which objects are drawn or painted, used in the production of animated cartoons.

Also, in case you didn’t already know, clues that end in question marks indicate a play on words in the clue itself or the answer. In other words, don’t take these clues too literally.

See the full puzzle here.

CLUE: Nurse, e.g. (5 letters)

Christopher Furlong/Getty ImagesThink of ‘nurse’ as a verb, not a noun.

Answer: Sip on

Explanation: The clue refers to the act of breastfeeding, not to the profession.

See the full puzzle here.

CLUE: Brother powder? (5 letters)

Chris Jackson/Getty ImagesDon’t take this clue at face value.

Answer: Toner

Explanation: Brother is a Japanese company that makes and sells printers, among other home and business products. Toner is a powder used in laser printers and photocopiers.

See the full puzzle here.

CLUE: Strips in geography class (6 letters)

Answer: Isthmi

Explanation: An isthmus is a narrow strip of land that connects two larger areas across a body of water. The plural form of isthmus is isthmi.

See the full puzzle here.

CLUE: Colds that last a long time (7 letters)

Scott Olson/Getty ImagesThere are several interpretations of the word ‘cold.’

Answer: Ice ages

Explanation: Put very simply, ice ages are periods of long-term reductions in the Earth’s temperature.

See the full puzzle here.

CLUE: Whirlybird (9 letters)

Wikimedia CommonsA whirlybird isn’t a type of bird.

Answer: Eggbeater

Explanation: Whirlybird and eggbeater are both antiquated synonyms for helicopter.

See the full puzzle here.

CLUE: One charging a flat rate? (8 letters)

Vera Kandybovich/ShutterstockThink outside the box for this one.

Answer: Landlord

Explanation: A flat is another word for an apartment. Landlords charge their tenants rent.

See the full puzzle here.

CLUE: Prepare to get juice from (6 letters)

Answer: Plug in

Explanation: “Juice” is a colloquial term that describes the amount of power a battery has or lacks. To charge an electronic device, you need to plug it in.

See the full puzzle here.

CLUE: Kicks under? (10 letters)

Alex Livesey/Getty ImagesCarefully consider the word ‘kicks.’

Answer: Rubber sole

Explanation: “Kicks” is a colloquial term for shoes, usually sneakers. The underside of a shoe is its sole. Many shoes have rubber soles.

See the full puzzle here.

CLUE: Rubber from the Middle East (7 letters)

Jon Buckle/Getty ImagesIf you’re still stumped, start thinking about popular movies.

Answer: Aladdin

Explanation: Disney’s “Aladdin” is set in the fictional city of Agrabah near the Jordan River in the Middle East. In the movie, Aladdin rubs a lamp and meets the Genie, who grants him three wishes.

See the full puzzle here.

CLUE: Quick board meeting? (10 letters)

Paul Bence/UnsplashYour mind probably jumps to a business meeting.

Answer: Speed chess

Explanation: Chess is a classic board game with two players. Speed chess, or fast chess, is a variation on the original game in which each player is given a limited amount of time to make a move.

See the full puzzle here.

CLUE: Lads who spend a lot of time looking at the net? (8 letters)

VFS Digital Design/FlickrIt’s not what you think.

Answer: Ball boys

Explanation: The word “net” refers not to the internet but to the net in basketball.

See the full puzzle here.

CLUE: “Just throwing out there,” briefly (3 letters)

Justin Edmonds/GettyIf a clue is enclosed in quotation marks, the answer is often a familiar uttered saying.

Answer: IMO

Explanation: The acronym “IMO” is internet slang for “in my opinion.”

See the full puzzle here.

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