The word 不明 is formed through the direct, conceptual combination of its two constituent characters: 不 (bù), meaning "not", and 明 (míng), meaning "bright" or "clear". Its formation is fundamentally ideographic, where the intrinsic meaning of the second character is negated or reversed by the first. Imagine the concept of light or clarity (明) being visually and notionally obscured by a barrier of negation (不), resulting in a new, composite idea of "not bright" or "not clear". This seamlessly extends to abstract senses like "unknown" or "unidentified", where the lack of clarity is applied to information or circumstances, all derived from this core metaphorical image of light being extinguished or obscured.