The word 必需 is formed by combining two independent characters, each contributing core meaning to create a new, unified concept. The first character, 必 (bì), means "must" or "certainly", imparting a sense of inevitability and absolute necessity. The second, 需 (xū), means "to need" or "necessity", referring to something that is required. Their fusion is not merely additive but synergistic, where 必 intensifies 需, transforming a general need into an indispensable, compulsory requirement. Thus, the compound visually and conceptually represents an unavoidable need, something that is absolutely essential.