‘流行’ (liú xíng) literally combines ‘流’ (liú), meaning ‘to flow’ or ‘to spread’, and ‘行’ (xíng), meaning ‘to go’ or ‘to be in effect’. Together, they convey the idea of something spreading widely and being widely accepted—hence ‘to be popular’ or ‘fashionable’. It’s commonly used to describe trends in clothing, music, language, behavior, or even diseases (e.g., a virus spreading). As an adjective, it modifies nouns (e.g., 流行歌曲 ‘popular song’); as a verb, it stands alone or takes subjects (e.g., 这款手机很流行 ‘This phone model is very popular’).

The word carries a neutral-to-positive connotation and is widely used in both spoken and written Chinese. Unlike some synonyms, ‘流行’ emphasizes broad social adoption rather than mere personal preference or temporary novelty. It’s frequently heard in media, advertising, and everyday conversation when discussing what’s currently ‘in’.