Top Definition
A person who at first appears to be normal but who gradually, over time, reveals himself or herself to be nothing more than an idiot. Derived from a merging of the words "insidious" and "idiot".
"The guy sitting beside me on the plane seemed like a cool guy, but the more he kept talking, I came to realize that he was nothing more than an insidiot"
by fredogonefishin April 02, 2014

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A person who knowingly acts in a devious and treacherous way to sabotage another person's well-being while simultaneously putting their own well being at risk.
The insidiot did everything in her power to ruin her ex-husband's business with no regard for the ill-effects it would have on her financial health.
by KMUSE July 02, 2013

The Urban Dictionary Mug

Lotsa space for your liquids.

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The Urban Dictionary Mug

Lotsa space for your liquids.

Buy the mug

The Urban Dictionary Mug

Your favorite word on a white mug.

Create a mug

The Urban Dictionary Mug

One side has the word, one side has the definition. Microwave and dishwasher safe. Lotsa space for your liquids.

Buy the mug

The Urban Dictionary T-Shirt

Soft and offensive. Just like you.

Buy the t-shirt

The Urban Dictionary T-Shirt

Smooth, soft, slim fit American Apparel shirt. Custom printed. 100% fine jersey cotton, except for heather grey (90% cotton).

Buy the t-shirt