The word "菲菲" is formed by duplicating the character 菲, which is a phono-semantic compound composed of the radical 艹 (cǎo), indicating its association with plants, and the component 非 (fēi), which primarily provides its phonetic sound. This repetition results in a disyllabic adjective that intensifies the meaning, often used to describe something lush, abundant, or fragrant, particularly in reference to plants or atmospheres.