something crescent-shaped, in particular 月牙形的物体,尤指 ■an arched aperture or window, especially one in a domed ceiling (尤指在建筑物穹顶上的)弧形空间;半圆壁弧形窗 ■a crescent-shaped or semicircular alcove containing something such as a painting or statue 弧形(壁)画;弧形装饰物 ■a fortification with two faces forming a projecting angle, and two flanks 眼镜堡 ■(Christian Church)a holder for the consecrated host in a monstrance (基督教)(在圣体匣内夹住圣饼的)新月形夹子(或水晶匣子) ■a ring fixed to a vehicle, by which it can be towed (车辆的)牵引环
语源
late 16th cent. (denoting a semicircular horseshoe): from French, diminutive of lune 'moon', from Latin luna