The word **彻夜** is formed through a logical and common Chinese word-formation method where two meaningful characters combine to create a new, specific meaning. The first character, **彻** (chè), carries the meaning of "thorough," "penetrating," or "through to the end." The second character, **夜** (yè), means "night." When combined, they create the compound **彻夜**, which functions as an adverb meaning "throughout the whole night" or "all night long." The formation is essentially descriptive: **彻** modifies **夜** to indicate the complete and unbroken duration of the nighttime period.