monitor

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. [ 1913 Webster ]

You need not be a monitor to the king. Bacon. [ 1913 Webster ]

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. [ 1913 Webster ]

3. (Zool.) 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. [ 1913 Webster ]

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. [ 1913 Webster ]

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. [ 1913 Webster ]

6. A monitor nozzle. [ Webster 1913 Suppl. ]

Monitor top, the raised central portion, or clearstory, of a car roof, having low windows along its sides. [ 1913 Webster ]