特殊 (tèshū) is an adjective meaning 'special, unusual, extraordinary' — it describes something that is out of the ordinary or different from the norm. It is more neutral and formal than 特别 (tèbié), which can also mean 'especially' as an adverb, and it contrasts with 非凡 (fēifán), which carries a stronger, more literary sense of 'remarkable' or 'extraordinary'.