The word "过敏性" is formed by sequentially combining three characters: 过 (guò), meaning "excess" or "over"; 敏 (mǐn), meaning "sensitive" or "sensitivity"; and 性 (xìng), meaning "nature" or "property". Together, they create a compound term where 过 modifies 敏 to convey "excessive sensitivity", and 性 nominalizes it, resulting in a word that denotes the condition of being allergic or having hypersensitivity.