quatrefoil

詳細解釋：

quat.re.foil

n.（名詞）
A representation of a flower with four petals or a leaf with four leaflets, especially in heraldry.
四小葉複葉，十字花：由一朵花和四片花瓣或一片葉子和四片小葉組成的圖紋，尤見於紋章
Architecture Tracery or an ornament with four foils or lobes.
【建築學】 四葉飾：有四片葉子或裂片的窗花格或裝飾品

來源：
Middle English quaterfoile
中古英文 quaterfoile
Old French quatre [four] * see quatrain
古法文 quatre [四] *參見 quatrain
Old French foil [leaf] * see foil 2
古法文 foil [葉子] *參見 foil2