Green’s Dictionary of Slang

a fool, an idiot.

a.1623		W. Camden Works (Johnson) n.p.: abject, base-minded, false-hearted, coward, or nidget [F&H].
c.1698		B.E. Dict. Canting Crew n.p.: Nigit a Fool.
1725		New Canting Dict. [as cit. c.1698].
1737, 1759, 1760, 1776		Bailey Universal Etym. Eng. Dict. [as cit. c.1698].
1785, 1788, 1796		Grose Classical Dict. of the Vulgar Tongue.