Under the weather — Feeling slightly ill or unwell. The expression describes a mild, temporary physical condition — a cold, a headache, an upset stomach, or general fatigue — rather than a serious illness. It suggests that someone is not quite at their best but is not in any danger.
Meaning in Detail
When someone says they are feeling “under the weather”, they are politely signalling that they feel a little unwell without going into detail. It is one of those handy idioms that communicates mild sickness gently and without drama. A person who is under the weather might have a runny nose, feel tired, or simply feel off colour — but they are not seriously ill, and the condition is usually expected to pass on its own with rest.
The idiom is extremely common in both British and American English and sits comfortably in informal and neutral registers. You will hear it in workplaces, in everyday conversation, and in casual written exchanges such as emails or text messages. It is rarely used in formal writing or medical contexts, where plain language such as “unwell” or “ill” is preferred. For ESL learners at B1 level and above, it is a highly useful expression to add to your active vocabulary.
Origin & History
The phrase comes from the world of sailing. In the age of sail, when a crew member fell ill or suffered from seasickness during a storm, they were sent below deck to rest and recover in a sheltered part of the ship. Being literally positioned beneath the weather — sheltered from the wind, rain, and heaving seas above — gave rise to the figurative expression. The phrase appears in written records from the early 19th century and became firmly established in everyday English as maritime vocabulary filtered into common speech ashore.
By the mid-19th century the idiom had shed its nautical specificity and was being used by landlubbers simply to mean feeling unwell. Its earliest printed appearances are found in American English, though the nautical context that gave birth to it would have been equally familiar to British seafarers and coastal communities. Today the expression is so well established that most speakers are entirely unaware of its origins at sea.
Example Sentences
| Sentence | Context |
|---|---|
| I'm feeling a bit under the weather today so I stayed home from work. | Workplace absence due to mild illness |
| She was under the weather all weekend and barely left the sofa. | Mild illness lasting several days |
| He sounded quite under the weather on the phone, so we moved the meeting to Thursday. | Rescheduling plans due to illness |
How to Use It
“Under the weather” is an informal to neutral expression suitable for spoken conversation, casual emails, text messages, and everyday writing. It works well when you want to mention illness briefly and politely without dwelling on symptoms. You can use it in the first person (“I'm feeling under the weather”), the third person (“She's been under the weather this week”), or as a simple description (“He looks a bit under the weather”).
- Only for mild illness: Reserve this idiom for colds, headaches, fatigue, and similar minor complaints. Using it to describe a serious or life-threatening condition would be a significant understatement and could cause confusion or offence.
- Always include “the”: The definite article is fixed and required. Saying “under weather” without “the” sounds unnatural and incorrect to native speakers.
- Avoid formal contexts: In a doctor's letter, an official report, or academic writing, choose straightforward vocabulary such as “unwell” or “ill” rather than an idiom.
Common Mistakes
Mistakes to Avoid
I'm feeling under weather today.
I'm feeling under the weather today. — The definite article “the” is always required in this fixed phrase.
She's very under the weather — she might need an operation.
She's a bit under the weather — she's got a cold. — The idiom only fits mild illness; for serious conditions, use plain language.
Similar Idioms
Practise This Idiom
Practice English Idioms
Use these exercises to master idioms in context: