A Tom Noddy is a very foolish or half-witted person, “a noodle.” The marine birds called Noddies are so silly that anyone can go up to them and knock them down with a stick. A donkey is called a Neddy Noddy. Minshew has a capital guess derivation, well fitted for a Dictionary of Fable. He says, “Noddy, a fool, so called because he nods his head when he ought to speak.” Just as well derive wise-man from why, because he wants to know the why of everything.
Source: Dictionary of Phrase and Fable, E. Cobham Brewer, 1894
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