Under the Weather

An expression meaning to feel ill, unwell or below one’s usual condition.

The phrase is frequently claimed to have a nautical origin, sometimes linked to sick sailors sheltering below deck from severe weather. That explanation is popular but not securely documented, so it is better treated as an uncertain origin rather than established maritime history.

In modern use, the expression applies broadly to minor illness or low spirits and does not necessarily refer to seasickness or exposure to weather.