The word 不用 is formed by directly combining two independent, fundamental characters: 不 (bù), which means "not" or "no", and 用 (yòng), which means "to use" or "to need". Their formation is visually and conceptually straightforward, where the negation 不 is placed before the action 用, creating a literal, composite idea of "not use" or "do not need". This fusion results in a single, fixed unit whose combined meaning has condensed over time into a common expression for "no need" or "unnecessary", functioning as a holistic concept rather than just a sum of its parts.