The word "不肖" is formed by directly combining the character "不", meaning "not", as a negating prefix, with the character "肖", meaning "to resemble" or "to be like". This creates a literal meaning of "not resembling", which in classical Chinese context specifically denotes a person who does not resemble the virtuous character or legacy of their predecessors, thus conveying the sense of being unworthy or unfilial. The formation is purely compositional, where the negation modifies the core concept of resemblance to express a derived ethical judgment.