Fender is the portion covering your tyres, all four of them. eg the front right fender is the part starting from where the bumper ends to where the right front door begins. From the hood/bonnet to the tyre. That is a fender in the car. There are other meanings to it also, like intrument to play music, etc
This would be a front left fender in a car

this is how your car would look like without the front left fender.
