The word 不必 is formed through the direct and logical combination of two fundamental characters: 不 (bù), meaning "not", and 必 (bì), meaning "must" or "necessarily". It is constructed by placing the negation directly before the concept of obligation or necessity, thereby creating a single conceptual unit that semantically fuses to express the idea of "not having to" or "need not". This formation follows a common pattern in Chinese where an adverb of negation modifies a following modal or stative verb to produce a new, compound negation of a specific state or action.