| 1. | any of various objects or spaces of crescentlike or semicircular outline or section. |
| 2. | Architecture. (in the plane of a wall) an area enframed by an arch or vault. |
| 3. | a painting, sculpture, or window filling such an area. |
| 4. | Fortification. a work consisting of a salient angle with two flanks and an open gorge. |
| 5. | Ordnance. a towing ring in the trail plate of a towed vehicle, as a gun carriage. |
| 6. | Ecclesiastical. Luna (def. 3). |
| 1. | the ancient Roman goddess personifying the moon, sometimes identified with Diana. |
| 2. | (in alchemy) silver. |
| 3. | (lowercase ) Also, lunette. Ecclesiastical. the crescent-shaped receptacle within the monstrance, for holding the consecrated Host in an upright position. |

lunette
arching aperture in a wall or concave ceiling. It may be crescent-shaped or semicircular. The word is the French diminutive of lune, "moon." Lunettes may function as windows, they may form a cove for ornament or statuary, or they may be simply a section of wall framed by an arch or vault. In the last case, the area will sometimes be decorated with a mural.
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