What does the word "Nincumpoop" mean? How about "scallywag?"?

nincompoop - stupid or an idiot.

Oxford Dictionary has a great website. http://www.oxforddictionaries.com/

Both words can be found in any online dictionary, but the correct spelling is "nincompoop", which means "a person who is silly or scatter-brained.

A "scallywag" is someone mischievous or someone who behaves with little regard to laws or rules.

A nincompoop is a dumb, stupid person.

A scallywag is a word not often used anymore in American English. A scallywag is a person who misbehaves or who can cheat others, but who is not a horrible criminal.

Both in native English are less harsh than so far suggested, being more of a mild rebuke of some silly behavior.

Silly person is a nincumpoop. A mean, decietful evil person is a skallawag.