An idiot.
Anything in the shape of a circle or torus.
A deep-fried piece of dough or batter, commonly made in a toroidal or ellipsoidal shape, and mixed with various sweeteners and flavors, sometimes filled with jelly, custard, or cream.
A peel-out or skid-mark in the shape of a donut; a 360-degree skid.
A spare tire, smaller and less durable than a full-sized tire, only intended for temporary use.
A toroidal cushion typically used by hemorrhoid patients.
An error; a blunder.
A pitch which was intended to be pitched in a hard-to-hit location, but instead ends up in an easy-to-hit place.
To understand wrongly, taking one thing or person for another.