Understanding English idioms
An idiom is a fixed, multi-word expression whose meaning cannot be predicted from its individual words. Its sense is figurative and conventional — settled by long use rather than derived from grammar or vocabulary. A learner who reads break the ice, spill the beans, or bite the bullet literally arrives at the wrong meaning; fluent speakers recognise the established figurative sense instead.
The word “idiom”
The term descends from Ancient Greek ἰδίωμα (idiōma), “a distinctive feature or peculiar phrasing”, itself from ἴδιος (idios), “one’s own” or “private”. An idiom was therefore something particular to a given language or community. The word entered English in the late sixteenth century by way of Latin and French, and its sense has since narrowed to expressions whose meaning is not recoverable from their parts.
Where idioms come from
Most idioms began as literal descriptions of ordinary activity and kept their figurative sense long after the activity itself faded from daily life. Grouped by the domain that produced them:
| Source | Example idioms |
|---|---|
| Farming | put all your eggs in one basket , reap what you sow , make hay while the sun shines |
| The sea | show your true colours , three sheets to the wind , in the same boat |
| Hunting | bark up the wrong tree , call off the dogs |
| Sport | throw in the towel , step up to the plate , move the goalposts |
| The Bible | the blind leading the blind , a wolf in sheep’s clothing , the writing on the wall , forbidden fruit |
| Shakespeare | a wild-goose chase , break the ice , wear your heart on your sleeve , it’s all Greek to me |
Literal reading vs settled meaning
The defining property of an idiom is the gap between a literal reading of its words and its conventional meaning. That gap is the main reason idioms resist word-for-word translation.
| Idiom | Literal reading | Actual meaning |
|---|---|---|
| kick the bucket | Kicking a pail | To die. |
| let the cat out of the bag | Releasing a cat from a bag | To reveal a secret, often by accident. |
| cost an arm and a leg | Surrendering two limbs | To be extremely expensive. |
| bite the bullet | Clenching a bullet in the teeth | To face something painful with resolve. |
Idioms in frequent use
These occur constantly in everyday English. Each links to its full entry, with examples and register.
| Idiom | Meaning |
|---|---|
| a piece of cake | Something very easy. |
| once in a blue moon | Very rarely. |
| under the weather | Slightly unwell. |
| hit the nail on the head | To identify something exactly. |
| burn the midnight oil | To work late into the night. |
| call it a day | To stop work for the time being. |
| the elephant in the room | An obvious problem that no one addresses. |
| when pigs fly | Never; on an occasion that will not come. |
| kill two birds with one stone | To achieve two aims with a single action. |
| pull someone’s leg | To tease someone in a friendly way. |
Idioms, proverbs, and change
An idiom is a figurative expression; a proverb is a compact statement of general advice, such as “honesty is the best policy”. The two categories overlap but are not identical: not every proverb is an idiom, and not every idiom is a proverb.
The stock of idioms also shifts over time. cut the Gordian knot and curry favour survive long after their origins — an ancient Greek legend and medieval horse-grooming — were forgotten, while newer coinages continue to enter the language through technology and media.
Why idioms matter
Idiomatic language saturates ordinary speech, film, and journalism, so comprehension depends on recognising it. For teachers, idioms repay explicit instruction: they are memorable, culturally revealing, and a reliable source of listening and reading difficulty when left untaught. Understanding far more idioms than one actively produces is the realistic goal for most learners.
Browse the full collection in the A–Z idiom index, or tell us about an idiom you’d like added.