The word 务必 (wùbì), meaning "must" or "imperatively", is formed through the combination of two semantically reinforcing characters: 务 (wù), which carries the core meaning of "affair" or "task" but here implies "must" or "to devote effort to", and 必 (bì), meaning "necessarily" or "certainly". Their union creates a compound adverb where each character intensifies the other, producing a strong sense of obligation and necessity that is more emphatic and formal than either character alone, effectively conveying a non-negotiable requirement or earnest exhortation.