四季 literally means 'four seasons' and refers collectively to spring, summer, autumn (or fall), and winter — the four natural divisions of the year based on climate and astronomical cycles. The first character 四 means 'four', a cardinal numeral, while 季 means 'season', a noun denoting a major time period in the annual cycle. Together, they form a fixed, unchangeable compound noun that is always used in the plural sense; it does not take measure words or plural markers like 们.

This term appears frequently in descriptions of climate, geography, agriculture, poetry, and daily life — for example, when talking about seasonal clothing, food, festivals, or regional weather patterns. It carries a neutral, slightly literary tone and is common in both spoken and written Chinese, especially in educational, cultural, or descriptive contexts. Unlike English, where 'the four seasons' may be used with 'the', 四季 is typically used without any article or demonstrative in Chinese.