What is "monitor top"

Monitor \Mon"i*tor\, n. [L., fr. monere. See Monition, and cf. Mentor.]

1. One who admonishes; one who warns of faults, informs of duty, or gives advice and instruction by way of reproof or caution.

   You need not be a monitor to the king.
   --Bacon.

2. Hence, specifically, a pupil selected to look to the school in the absence of the instructor, to notice the absence or faults of the scholars, or to instruct a division or class.

3. (Zo["o]l.) Any large Old World lizard of the genus Varanus; esp., the Egyptian species ( Varanus Niloticus), which is useful because it devours the eggs and young of the crocodile. It is sometimes five or six feet long.

4. [So called from the name given by Captain Ericson, its designer, to the first ship of the kind.] An ironclad war vessel, very low in the water, and having one or more heavily-armored revolving turrets, carrying heavy guns.

5. (Mach.) A tool holder, as for a lathe, shaped like a low turret, and capable of being revolved on a vertical pivot so as to bring successively the several tools in holds into proper position for cutting.

6. A monitor nozzle.

   Monitor top, the raised central portion, or clearstory, of a car roof, having low windows along its sides.