Winter season refers to the coldest time of year, typically spanning December to February in the Northern Hemisphere. The character 冬 (dōng) means 'winter' on its own and evokes cold weather, snow, and hibernation; 季 (jì) means 'season' and is used in all four seasonal terms—spring, summer, autumn, and winter. Together, 冬季 emphasizes the full seasonal period rather than just the concept of winter, making it more formal and time-specific than 冬 alone.

This term is commonly used in weather reports, school calendars (e.g., winter break), travel planning (e.g., winter sports), and official documents. It appears frequently in compound phrases like 冬季奥运会 (Winter Olympics) or 冬季服装 (winter clothing). Unlike colloquial expressions such as 天冷了 ('it’s gotten cold'), 冬季 carries a clear temporal boundary and is neutral in register—suitable for both spoken and written contexts.