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Idioms are special phrases where the words together mean something different from what they say one by one. People use them to make talking and writing more colorful and exciting when describing tasks that cannot be done. In this lesson, you will learn fifty unique idioms related to things that are completely impossible.
In this lesson, we’ll look at idioms that mean impossible, hopeless, or out of reach. Let’s get started and explore some of these helpful expressions.
Idioms for Impossible
1. Once in a blue moon
Definition: Something that happens so rarely it is practically impossible to expect.
Used in a Sentence: Snow falling in our warm desert town happens only once in a blue moon. / My little brother cleans his entire bedroom without being asked once in a blue moon.
Similar Expressions: Very rarely / Hardly ever
2. When pigs fly
Definition: Used to describe an event that will never happen because it is impossible.
Used in a Sentence: My cat will learn to speak French when pigs fly. / He said he would share his candy when pigs fly across the sky.
Similar Expressions: Never going to happen / Absolutely impossible
3. Catching smoke with bare hands
Definition: Trying to accomplish a task that has no physical substance or chance of success.
Used in a Sentence: Trying to keep secrets hidden forever is like catching smoke with bare hands. / Fixing that broken plastic toy with only tape was like catching smoke with bare hands.
Similar Expressions: Chasing shadows / Impossible task
4. Pulling teeth
Definition: Describing a task that is painfully difficult and requires immense effort.
Used in a Sentence: Getting my younger brother to put his shoes on is like pulling teeth. / Trying to make him clean his desk felt like pulling teeth all afternoon.
Similar Expressions: Extremely hard work / Painful struggle
5. Looking for a needle in a haystack
Definition: Searching for a tiny object in a massive space where it is nearly impossible to find.
Used in a Sentence: Finding my lost contact lens on the grassy playground felt like looking for a needle in a haystack. / Searching for that specific green marble in the toy chest is like looking for a needle in a haystack.
Similar Expressions: Impossible search / Hidden quest
6. Barking up the wrong tree
Definition: Pursuing a completely mistaken path that leads to no results.
Used in a Sentence: If you think I took your colored pencils, you are barking up the wrong tree. / The detective realized he was barking up the wrong tree when looking for clues.
Similar Expressions: Mistaken pursuit / Wrong direction
7. Carrying water in a sieve
Definition: Doing a task that is entirely useless because it cannot hold anything.
Used in a Sentence: Trying to fix that leaking boat with holes is like carrying water in a sieve. / Arguing with him about sports rules is like carrying water in a sieve.
Similar Expressions: Useless effort / Pointless labor
8. Making a silk purse out of a sow’s ear
Definition: Trying to turn something low quality into something wonderful and refined.
Used in a Sentence: Trying to make this old torn tent look brand new is like making a silk purse out of a sow’s ear. / Redecorating that dusty shed was like making a silk purse out of a sow’s ear.
Similar Expressions: Impossible upgrade / Hopeless makeover
9. Raining cats and dogs
Definition: A heavy storm that feels overwhelmingly powerful and disruptive.
Used in a Sentence: We had to cancel our baseball game because it started raining cats and dogs. / Looking outside, I saw it was raining cats and dogs before school.
Similar Expressions: Heavy downpour / Massive storm
10. Reach for the moon
Definition: Setting a goal that is so grand it feels almost impossible to achieve.
Used in a Sentence: The teacher told us to always reach for the moon with our creative writing. / Winning an international science prize is like trying to reach for the moon.
Similar Expressions: Impossible goal / Grand ambition
11. Hitting your head against a brick wall
Definition: Struggling repeatedly with a problem that refuses to change.
Used in a Sentence: Trying to convince my puppy to stay off the couch feels like hitting your head against a brick wall. / Working on that unanswerable math riddle felt like hitting your head against a brick wall.
Similar Expressions: Endless frustration / Useless persistence
12. Square peg in a round hole
Definition: A person or thing that does not fit into a situation at all.
Used in a Sentence: Trying to put that giant square box into the tiny circular shelf felt like a square peg in a round hole. / He felt like a square peg in a round hole during the advanced physics seminar.
Similar Expressions: Complete mismatch / Awkward fit
13. Pushing water uphill
Definition: Attempting an action that goes against natural forces and cannot succeed.
Used in a Sentence: Trying to change his stubborn mind about the rules is like pushing water uphill. / Cleaning up leaves during a windy storm is like pushing water uphill.
Similar Expressions: Uphill battle / Impossible effort
14. Shooting at the moon
Definition: Attempting a goal so lofty that success is out of reach.
Used in a Sentence: Expecting to build a working rocket ship in our garage is like shooting at the moon. / She knew she was shooting at the moon when she applied for the national contest.
Similar Expressions: Unrealistic dream / Impossible aim
15. Trying to teach a fish to climb trees
Definition: Asking someone to do something completely outside their natural abilities.
Used in a Sentence: Asking our sleepy class dog to solve calculus problems is like trying to teach a fish to climb trees. / Expecting me to fix a car engine with no tools is like trying to teach a fish to climb trees.
Similar Expressions: Impossible expectation / Unnatural task
16. Chasing the wind
Definition: Pursuing something that is intangible, fleeting, and impossible to catch.
Used in a Sentence: Trying to catch every falling autumn leaf before it lands is like chasing the wind. / Worrying about things you cannot control is just like chasing the wind.
Similar Expressions: Futile pursuit / Empty chase
17. Waiting for hell to freeze over
Definition: Waiting for an event that will never, ever happen.
Used in a Sentence: He said he would clean his locker when hell freezes over. / We could wait for hell to freeze over before my sister stops singing.
Similar Expressions: Waiting forever / Endless wait
18. Building castles in the air
Definition: Dreaming up grand plans that have no foundation in reality.
Used in a Sentence: Stop building castles in the air and start working on your homework. / Designing an imaginary treehouse with elevators is just building castles in the air.
Similar Expressions: Unrealistic dreams / Daydreaming plans
19. Trying to nail jelly to a tree
Definition: Attempting to organize or control something that is completely slippery and unstable.
Used in a Sentence: Trying to get the unruly kindergarten class to stand in a straight line was like trying to nail jelly to a tree. / Explaining the complex rules to him felt like trying to nail jelly to a tree.
Similar Expressions: Impossible control / Slippery task
20. Finding water in a desert
Definition: Searching for a scarce resource when none exists anywhere nearby.
Used in a Sentence: Looking for an extra pencil in this empty classroom is like finding water in a desert. / Trying to buy that sold-out toy ticket was like finding water in a desert.
Similar Expressions: Hopeless search / Scarce find
21. Turning lead into gold
Definition: An ancient impossible dream of transforming cheap metal into treasure.
Used in a Sentence: Expecting my messy bedroom to clean itself is like turning lead into gold. / Trying to make this burnt toast taste gourmet is like turning lead into gold.
Similar Expressions: Magic transformation / Impossible alchemy
22. Treading on water
Definition: Doing an action that lacks solid ground or support to keep you up.
Used in a Sentence: Without studying for the test, I felt like I was treading on water during class. / Relying on rumors for your history project is like treading on water.
Similar Expressions: Unstable footing / Lacking support
232. Whistling in the dark
Definition: Trying to show bravery while facing an intimidating and hopeless situation.
Used in a Sentence: Walking past the spooky old mansion at night was just whistling in the dark. / He pretended to be confident about the hard test, but it was whistling in the dark.
Similar Expressions: False courage / Hopeless bravado
24. Trying to squeeze water from a stone
Definition: Attempting to get resources or help from someone who has nothing to give.
Used in a Sentence: Asking my brother for extra allowance money is like trying to squeeze water from a stone. / Trying to get a straight answer out of him is like trying to squeeze water from a stone.
Similar Expressions: Getting nothing / Impossible extraction
25. Eating your soup with a fork
Definition: Using the completely wrong tool to accomplish an everyday task.
Used in a Sentence: Trying to eat cereal with a toothpick is like eating your soup with a fork. / Using a tiny butter knife to cut down a tree is like eating your soup with a fork.
Similar Expressions: Wrong tool / Ineffective method
26. Catching a falling star
Definition: Trying to capture something magical that vanishes instantly.
Used in a Sentence: Trying to hold onto childhood memories forever is like catching a falling star. / Winning the lottery on your first try is like catching a falling star.
Similar Expressions: Impossible capture / Fleeting dream
27. Painting the sky
Definition: Attempting to alter or decorate something that is vast and uncontrollable.
Used in a Sentence: Trying to change everyone’s opinion on the movie is like painting the sky. / Arguing about the weather forecast is like painting the sky.
Similar Expressions: Unchangeable task / Futile decorating
28. Drawing water with a bottomless bucket
Definition: Performing endless labor that yields zero results.
Used in a Sentence: Trying to keep the playroom clean with toddlers around is like drawing water with a bottomless bucket. / Studying for a test without opening the book is like drawing water with a bottomless bucket.
Similar Expressions: Endless labor / Fruitless work
29. Counting your chickens before they hatch
Definition: Assuming success on an uncertain event before it actually happens.
Used in a Sentence: Do not buy a trophy yet because counting your chickens before they hatch is risky. / He planned his celebration speech before the race started, counting his chickens before they hatch.
Similar Expressions: Premature celebration / Assuming success
30. Walking on burning coals
Definition: Facing an intensely painful and seemingly impossible ordeal.
Used in a Sentence: Waiting for the principal to read my disciplinary note felt like walking on burning coals. / Taking that brutal math final exam felt like walking on burning coals.
Similar Expressions: Painful ordeal / Stressful trial
31. Catching the wind in a net
Definition: Trying to trap something that cannot be physically contained.
Used in a Sentence: Trying to catch rumors before they spread is like catching the wind in a net. / Holding water in your cupped hands is like catching the wind in a net.
Similar Expressions: Impossible containment / Futile trap
32. Attempting the impossible
Definition: Direct phrase describing a task that defies all odds of completion.
Used in a Sentence: Solving the century-old math puzzle felt like attempting the impossible. / Climbing that steep vertical cliff without ropes was attempting the impossible.
Similar Expressions: Defying odds / Hopeless attempt
33. Beyond reach
Definition: Located at a distance where success or acquisition is impossible.
Used in a Sentence: The top shelf cookies were beyond reach for the small toddler. / Winning first place felt beyond reach after my early mistake.
Similar Expressions: Unattainable / Out of grasp
34. Out of the question
Definition: A proposal or idea that is completely unacceptable and impossible.
Used in a Sentence: Staying up until midnight on a school night is completely out of the question. / Mom said buying a pony for the backyard was out of the question.
Similar Expressions: Unacceptable / Impossible idea
35. Not a snowball’s chance in hell
Definition: Having zero probability of success under any circumstances.
Used in a Sentence: Our soccer team had not a snowball’s chance in hell against the state champions without practice. / Trying to finish this fifty-page book in ten minutes has not a snowball’s chance in hell.
Similar Expressions: Zero chance / Impossible odds
36. Tilting at windmills
Definition: Fighting imaginary enemies or pursuing impossible, pointless battles.
Used in a Sentence: Arguing with online strangers about cartoon shows is just tilting at windmills. / He spent all afternoon tilting at windmills over a minor misunderstanding.
Similar Expressions: Pointless fight / Imaginary battle
37. Searching for El Dorado
Definition: Looking for a mythical, impossible treasure that does not exist.
Used in a Sentence: Searching for my lost toy in the deep woods felt like searching for El Dorado. / Looking for perfection in every single homework assignment is like searching for El Dorado.
Similar Expressions: Mythical search / Impossible treasure
38. Crossing a bridge before you come to it
Definition: Worrying about impossible future problems that may never happen.
Used in a Sentence: Do not panic about college exams in middle school; you are crossing a bridge before you come to it. / Worrying about a test next month is crossing a bridge before you come to it.
Similar Expressions: Premature worry / Future stress
39. Trying to fit a square box into a round hole
Definition: Forcing an incompatible object or idea into a wrong space.
Used in a Sentence: Forcing that oversized book into the tiny backpack slot is like trying to fit a square box into a round hole. / Putting him in charge of art class was like trying to fit a square box into a round hole.
Similar Expressions: Incompatible fit / Wrong match
40. Biting off more than you can chew
Definition: Taking on a task so large and difficult it becomes impossible to finish.
Used in a Sentence: Registering for four sports at the same time meant I was biting off more than you can chew. / He realized he was biting off more than he could chew when building the giant model.
Similar Expressions: Overloading tasks / Too much work
41. Trying to catch a bullet with your teeth
Definition: Facing a dangerous and impossible challenge with no hope of success.
Used in a Sentence: Trying to argue against the strict school dress code rules felt like trying to catch a bullet with your teeth. / Facing the reigning chess champion as a beginner felt like trying to catch a bullet with your teeth.
Similar Expressions: Dangerous odds / Hopeless fight
42. Making bricks without straw
Definition: Trying to complete a project while lacking essential supplies and support.
Used in a Sentence: Asking us to bake a cake without any flour is like making bricks without straw. / Trying to do research without any internet access is like making bricks without straw.
Similar Expressions: Lacking supplies / Impossible work
43. Trying to turn back the clock
Definition: Attempting the impossible feat of reversing time.
Used in a Sentence: Wishing we could undo yesterday’s argument is like trying to turn back the clock. / Once the vase broke, trying to turn back the clock was impossible.
Similar Expressions: Reversing time / Impossible undo
44. Looking for a needle in the ocean
Definition: An exaggerated version of searching for something tiny in an endless space.
Used in a Sentence: Dropping my ring off the cruise ship deck meant looking for a needle in the ocean. / Finding my misplaced flash drive in the giant storage unit was like looking for a needle in the ocean.
Similar Expressions: Impossible find / Vast search
45. Trying to teach an old dog new tricks
Definition: Trying to change habits that are deeply ingrained and impossible to alter.
Used in a Sentence: Getting my grandfather to use a modern smartphone is like trying to teach an old dog new tricks. / Trying to change his stubborn morning routine is like trying to teach an old dog new tricks.
Similar Expressions: Hard to change / Stubborn habits
46. Walking on water
Definition: Performing a miraculous feat that normal people cannot possibly do.
Used in a Sentence: Expecting me to score five goals in my very first soccer game is expecting me to walk on water. / The teacher acted like getting an absolute ten on the hard quiz was walking on water.
Similar Expressions: Miraculous feat / Impossible standard
47. Sowing seeds in the sand
Definition: Doing hard work in a place where nothing can possibly grow.
Used in a Sentence: Giving study advice to someone who refuses to listen is like sowing seeds in the sand. / Trying to plant flowers in dry pavement is like sowing seeds in the sand.
Similar Expressions: Pointless effort / Barren work
48. Trying to lasso the wind
Definition: Attempting to physically grab and control something invisible.
Used in a Sentence: Trying to stop rumors from spreading in the hallway is like trying to lasso the wind. / Catching floating soap bubbles in a hurricane is like trying to lasso the wind.
Similar Expressions: Controlling air / Impossible capture
49. Reaching for the stars with a short ladder
Definition: Setting a goal with tools or abilities that are completely inadequate.
Used in a Sentence: Trying to build a treehouse with only a butter knife is like reaching for the stars with a short ladder. / Expecting to win the science fair without doing experiments is reaching for the stars with a short ladder.
Similar Expressions: Inadequate tools / Impossible goal
50. Trying to tame a hurricane
Definition: Attempting to control a massive, violent natural force that cannot be stopped.
Used in a Sentence: Trying to calm down an angry crowd during a dispute is like trying to tame a hurricane. / Managing my little brother’s chaotic birthday party felt like trying to tame a hurricane.
Similar Expressions: Uncontrollable force / Impossible control
Exercise to Practice
- Snow falling in our warm desert town happens only once in a blue moon.
- My cat will learn to speak French when pigs fly across the sky.
- Trying to keep secrets hidden forever is like catching smoke with bare hands.
- Getting my younger brother to put his shoes on is like pulling teeth every single morning.
- Finding my lost contact lens on the grassy playground felt like looking for a needle in a haystack.
- If you think I took your colored pencils, you are barking up the wrong tree because I was outside.
- Trying to fix that leaking boat with holes is like carrying water in a sieve.
- Trying to make this old torn tent look brand new is like making a silk purse out of a sow’s ear.
- We had to cancel our baseball game because it started raining cats and dogs outside.
- The teacher told us to always reach for the moon with our creative writing by lowering our standards.
- Trying to convince my puppy to stay off the couch feels like hitting your head against a brick wall.
- Trying to put that giant square box into the tiny circular shelf felt like a square peg in a round hole.
- Trying to change his stubborn mind about the rules is like pushing water uphill with no help.
- Expecting to build a working rocket ship in our garage is like shooting at the moon.
- Asking our sleepy class dog to solve calculus problems is like trying to teach a fish to climb trees.
Answer Key
- True
- True
- True
- True
- True
- True
- True
- True
- True
- False
- True
- True
- True
- True
- True
Conclusion
Learning these idioms helps you describe impossible tasks and hopeless situations in creative and colorful ways. Expanding your everyday vocabulary makes your stories and conversations much more engaging for everyone around you.
Try using one or two of these expressions the next time you talk with your classmates or family members. You will see how much fun it is to express your thoughts using vivid English phrases.
Frequently Asked Questions
What are some common idioms for impossible?
Common idioms include phrases like once in a blue moon, when pigs fly, and looking for a needle in a haystack. These expressions give a clear picture of tasks that cannot be done.
Why do we use idioms in English?
Idioms make our language more vibrant, colorful, and fun to speak. Instead of plain descriptions, they let us share feelings and challenges in creative ways.
How can I practice using idioms easily?
You can practice by picking one new idiom each day and using it in a sentence with a friend. Writing short stories or making up funny sentences also helps you remember them.
Are idioms difficult for beginners to learn?
Not at all, especially when you learn them through relatable topics like funny impossibilities. Context and example sentences make it easy to understand what they mean right away.
Can I use these idioms in school writing?
Yes, using idioms can make your stories and essays much more creative and fun to read. Just make sure you use them correctly so your meaning is clear to your teacher.
