The Chinese word 偷渡 (tōudù), meaning "to illegally cross a border" or "to stow away," is a compound formed by combining the morpheme 偷 (tōu), which means "to steal" or "to do secretly," with the morpheme 渡 (dù), which means "to cross over" (typically a body of water). The term thus literally and metaphorically constructs the concept of "secretly crossing," where 偷 conveys the illicit, covert nature of the action, and 渡 specifies the act of crossing a boundary, most commonly a national border. It functions as a verb-object structure where 偷 modifies the manner of the crossing performed by 渡, evolving into a fixed lexical unit that specifically denotes illegal immigration or unauthorized passage.