严丝合缝 yánsīhéfèng to fit perfectly Origin Definitions Defs Strokes Stroke Words Sentences Sents 严 嚴 yán adjective tight tight; closely sealed; leaving no gaps丝 絲 sī numeraladjective trace a tiny bit; a very small amount, often used in set phrases like 一丝不苟 yīsībùgǒu or 丝毫 sīháo合缝 合縫 héfèng to fit snugly to fit together perfectly without any gaps, such as for doors, windows, or joints