tracery
/ˈtreɪsərɪ; `tresərɪ/ n[U, C]
1 ornamental patternof stonework in a church window, etc （教堂窗户等上的）石制花饰. =>illus at App 1 见附录1插图, page viii.
2 decorative pattern resembling this 类似石制花饰的图案
the delicate traceries of frost on the window-pane 结在窗户玻璃上的精美的霜花.