边界 biānjiè HSK7 boundary Origin Definitions Defs Strokes Stroke Words Sentences Sents 边界线 biānjièxiàn boundary The line marking the geographical or political limit between two areas.边界层 biānjiècéng boundary layer 中俄边界协议 Zhōng'ébiānjièxiéyì Sino-Russian agreement Sino-Russian Border Agreement of 1991