Lunette

[loo-net] /luˈnɛt/

noun
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. (def 3).
/luːˈnɛt/
noun
1.
anything that is shaped like a crescent
2.
an oval or circular opening to admit light in a dome
3.
a semicircular panel containing a window, mural, or sculpture
4.
a ring attached to a vehicle, into which a hook is inserted so that it can be towed
5.
a type of fortification like a detached bastion
6.
(RC Church) Also called lune. a case fitted with a bracket to hold the consecrated host
n.

1570s, “semi-circular horseshoe,” from Middle French lunette (13c.), literally “little moon,” diminutive of lune “moon,” from Latin luna (see luna). Later applied to a wide range of objects and ornamentations resembling a crescent moon.