An outdoor cookstove used to cook hamburgers, hot dogs, shish kebabs, and barbecue steaks. They typically consist of a shallow pit (for placing charcoal, mesquite chips, lighter fluid, and other fire-related items, including fire), a cooking surface of parallel metal bars, and a metal lid.

Also, the act of cooking food on a grill.

Also, a kind of restaurant featuring food cooked on a grill, or at least allegedly cooked on a grill. Commonly combined with a bar so that it may be called a bar and grill. Also commonly featuring various tacky souvenirs and knickknacks stuck on the walls, chipper college-age waitstaff bedecked in buttons, pins, and ribbons, and a large variety of fruity drinks and margaritas.

Let's not forget: it's also a metal or plastic grating, usually decorative, covering a window or the front end of a car. On your car, it's the place where you have to pick all the dead bugs out of when you wash it.

And finally, the act of relentlessly interrogating or cross-examining someone.

Thanks to NatchLucid for the reminder about the restaurants...