The word 黑夜 (hēi yè) is formed by directly combining two meaningful characters: 黑 (hēi), which means "black" or "dark", and 夜 (yè), which means "night". It is a conceptual fusion where the first character describes the defining quality of the second, painting a vivid picture of "night" specifically in its characteristic state of "darkness". Thus, the compound naturally and intuitively evokes the complete, profound darkness of the night time.