纷 (fēn) means 'in disorder' or 'in profusion', and when reduplicated as 纷纷 (fēn fēn), it functions as an adverb meaning 'in droves', 'one after another', or 'in large numbers, rapidly and continuously'. The repetition intensifies the sense of multiplicity and simultaneity — like leaves falling all at once, or people arriving without pause. It often describes spontaneous, collective movement or action, especially involving people, animals, or natural phenomena.

This word frequently appears in written and formal spoken Chinese, especially in descriptive or narrative contexts — news reports, literature, or commentary. It typically modifies verbs (e.g., 落下, 涌来, 报名, 离开) and emphasizes both quantity and tempo. While it can describe physical motion (e.g., snowflakes falling), it’s also used figuratively for abstract actions like opinions emerging or messages pouring in.