lantern

1. (theater) Especially, a metal casing with lens used to illuminate a stage (e.g. spotlight, floodlight).

2. (architecture) An open structure of light material set upon a roof, to give light and air to the interior.Examples: "On such an afternoon, if ever, the Lord High Chancellor ought to be sitting here—as here he is—with a foggy glory round his head, softly fenced in with crimson cloth and curtains, addressed by a large advocate with great whiskers, a little voice, and an interminable brief, and outwardly directing his contemplation to the lantern in the roof, where he can see nothing but fog."; "The station also boasts a large semi-domed French pavilion roof with fish-scale tiles and iron cresting, plus a rectangular hall with arcaded upper storey and wooden lantern."

3. (architecture) A cage or open chamber of rich architecture, open below into the building or tower which it crowns.

4. (architecture) A smaller and secondary cupola crowning a larger one, for ornament, or to admit light.Examples: "the lantern of the cupola of the Capitol at Washington, or that of the Florence cathedral"

5. (engineering) A lantern pinion or trundle wheel.

6. (steam engines) A kind of cage inserted in a stuffing box and surrounding a piston rod, to separate the packing into two parts and form a chamber between for the reception of steam, etc.; a lantern brass.