An idiom is a phrase whose meaning cannot be worked out from its words. English speakers say it is raining cats and dogs without picturing any animals. Every language has thousands of these, and comparing them across languages is one of the more entertaining things you can do with a dictionary.
Heavy rain
| Language | Idiom | Literally |
|---|---|---|
| English | raining cats and dogs | — |
| French | il pleut des cordes | it's raining ropes |
| Spanish | llueve a cántaros | it's raining pitchers |
| German | es regnet Bindfäden | it's raining string |
| Dutch | het regent pijpenstelen | it's raining pipe stems |
| Portuguese | chove a cântaros | it's raining jugs |
| Greek | βρέχει καρεκλοπόδαρα | it's raining chair legs |
| Welsh | bwrw hen wragedd a ffyn | raining old women and sticks |
Several languages converge on long thin objects falling — ropes, string, pipe stems, chair legs — which is a reasonable description of heavy rain. English and Welsh went somewhere else entirely.
Something that will never happen
| Language | Idiom | Literally |
|---|---|---|
| English | when pigs fly | — |
| French | quand les poules auront des dents | when hens have teeth |
| Russian | когда рак на горе свистнет | when the crayfish whistles on the mountain |
| Dutch | als Pasen en Pinksteren op één dag vallen | when Easter and Pentecost fall on the same day |
| Italian | quando gli asini voleranno | when donkeys fly |
| Finnish | kun lehmät lentävät | when cows fly |
| Romanian | la paștele cailor | at the horses' Easter |
Impossibility idioms cluster around two images: animals doing what they cannot, and calendar events that cannot coincide. The Russian crayfish is the outlier, and it is specific enough that it survives as a recognisable cultural reference rather than as a generic phrase.
Not being quite right in the head
| Language | Idiom | Literally |
|---|---|---|
| English | a few sandwiches short of a picnic | — |
| German | nicht alle Tassen im Schrank haben | not have all the cups in the cupboard |
| Dutch | van het padje af zijn | to be off the little path |
| Swedish | ha en skruv lös | to have a screw loose |
| Polish | mieć nierówno pod sufitem | to have it uneven under the ceiling |
| Spanish | faltarle un tornillo | to be missing a screw |
The mechanical image — a loose or missing screw — recurs across several unrelated languages, and is recent enough that it must postdate widespread machinery.
It's not my problem
| Language | Idiom | Literally |
|---|---|---|
| English | not my circus, not my monkeys | borrowed from Polish |
| Polish | nie mój cyrk, nie moje małpy | not my circus, not my monkeys |
| German | nicht mein Bier | not my beer |
| French | ce n'est pas mes oignons | those aren't my onions |
| Japanese | 対岸の火事 | a fire on the opposite bank |
The English version is a recent direct borrowing from Polish, which is a reminder that idiom inventories are not closed — they gain entries when a phrase is vivid enough to travel.
Why translation fails on them
Idioms are stored as whole units. Their meaning is not composed from their parts, so any process working part by part produces nonsense. This is why machine translation, which has become very good at ordinary sentences, still produces conspicuous errors on idiomatic ones — and why a literal rendering is often a reliable signal that a phrase was idiomatic.
The corresponding advice for learners is to store them whole too. Learn il pleut des cordes as a single item meaning heavy rain, without dissecting it, exactly as you learned raining cats and dogs without asking questions.
Recognise early, use late
Comprehension is the priority: idioms are frequent in ordinary speech and missing one derails a sentence. Production is riskier, because register and currency are difficult to judge from outside — some idioms are dated, some regional, some faintly ridiculous in the mouth of a learner.
A reasonable rule is to use an idiom only after hearing it used naturally by someone whose register you would be comfortable borrowing. Until then, plain phrasing is always available and never sounds wrong.
Check the words inside the idiom
Idioms are learned whole, but the words still need looking up. NDT Studio's free offline dictionaries cover 45 language pairs.
Open the dictionary appFrequently asked questions
Why can't idioms be translated literally?
Because their meaning is not built from their parts. Kick the bucket means to die, and nothing about kicking or buckets gets you there. Translating word by word produces a phrase that is grammatical and meaningless, which is why machine translation still stumbles on them.
Do different languages share any idioms?
Many, through borrowing or shared cultural sources. Biblical and classical phrases recur across Europe, and modern English idioms spread widely through media. Independent coincidence also happens where the underlying image is obvious enough.
How should learners approach idioms?
Learn to recognise them long before trying to use them. Comprehension is what you need, since idioms are frequent in speech; production is risky because register and currency are hard to judge, and a misjudged idiom is more conspicuous than plain phrasing.