'Fā fēng' literally combines 'fā' (to emit, to become) and 'fēng' (madness, insanity), forming a verb meaning 'to go mad' or 'to lose one's mind'. It describes a sudden, often temporary, loss of rational control—ranging from extreme emotional agitation (e.g., rage or panic) to clinical psychosis. While historically rooted in traditional Chinese medical concepts of wind disturbing the mind, modern usage is mostly figurative and colloquial.

The term is frequently used hyperbolically in informal speech—for example, to express overwhelming stress ('I’m going crazy trying to finish this report') or irrational excitement ('She went nuts when she saw the concert tickets'). It carries strong connotations of loss of self-control and is rarely used in formal or clinical contexts, where terms like 'jīngshén shīcháng' (mental disorder) are preferred. Tone and context heavily influence whether it sounds humorous, alarming, or sympathetic.