An idiom is a phrase whose meaning you can't work out from the individual words — "piece of cake" has nothing to do with cake; it just means "very easy." English is full of them, and this guide covers ten you'll genuinely hear, each with a meaning and an example.
A quick warning up front: idioms are seasoning, not the meal. Native speakers use them less often than textbooks suggest, so the goal is to recognize many and produce just a few naturally.
Ten idioms worth knowing
Each of these is common, current, and safe to use once you're comfortable with it.
| Idiom | Meaning |
|---|---|
| Piece of cake | Very easy |
| Break a leg | Good luck (before a performance) |
| Under the weather | Slightly sick |
| Hit the sack | Go to bed |
| Cost an arm and a leg | Very expensive |
| Once in a blue moon | Very rarely |
| Call it a day | Stop working for now |
| On the fence | Undecided |
| Get cold feet | Lose your nerve before a big step |
| The ball is in your court | It's your decision now |
Seeing them in a sentence
Idioms click once you hear them in context. Here's each one at work.
| Example sentence | What it means |
|---|---|
| "The test was a piece of cake." | It was very easy. |
| "Break a leg out there!" | Good luck (before a show or exam). |
| "I'm a bit under the weather today." | I feel slightly sick. |
| "I'm beat — time to hit the sack." | I'm tired; I'm going to bed. |
| "The repair cost an arm and a leg." | It was very expensive. |
| "He got cold feet before the wedding." | He lost his nerve at the last moment. |
"Under the weather" is the perfect phrase for calling in sick: "I'm feeling under the weather, so I'll work from home today" is polite, natural, and a little softer than saying "I'm sick." "Break a leg" is your go-to before someone performs or takes a big exam — "good luck" works too, but "break a leg" sounds warmer and more in-the-know.
The honest part: idioms textbooks oversell
Some famous idioms are recognized by everyone but rarely actually said. The classic example is "it's raining cats and dogs." Every native speaker knows it, most will smile at it — and almost nobody says it. They say "it's pouring" instead.
Be careful with textbook idioms that feel dated. Lean on them too hard and you can sound like a book rather than a person. When in doubt, choose the plain version: "it's pouring," "it's freezing," "I'm exhausted." Save idioms for when they truly fit.
So treat idioms as a listening skill first. Learn to recognize a wide range — because people will use them around you — but pick just a handful of favorites to actually say, the ones that feel natural in your mouth.
Why idioms feel hard
Idioms and phrasal verbs (like "put up with" or "run into") are the real difficulty spike in English, because you can't decode them logically — you have to meet them one by one. That's normal, and it's covered honestly in our look at whether English is hard to learn.
Keep learning English
Idioms reward patient exposure: the more real English you hear, the more of them quietly click into place. Practice the common ones with audio and spaced repetition in the Pretalk app, and keep building the grammar underneath with our free English grammar guides.
