A device used for cutting cheese. These may be simply a knife designed specifically for cheese, usually looking somewhat like a stubby cleaver. More often it will be some type of utensil that uses a piece of wire to slice the cheese. The most common of these is a 'T' shaped device, the wire stretched taut by a small frame, with the handle set parallel to this frame. These will usually be adjustable so that you can cut slices of different thicknesses. You might also see cheese cutters that look like small cutting boards with a 'U' shaped metal bar, one arm of the 'U' set into the edge of the board, functioning as a hinge. The wire stretches between the tines of the 'U', and this slices down through the cheese. There will also be a groove in the board deep enough for the wire to cut completely through the cheese.

It also refers to a rather shapeless cap with a small brim in front. It is also called a Driver's cap, a Driving cap, or a flat cap. You've probably seen them in pictures of old-time motorists or movie directors.

Cheese cutter can also refer to other styles of hats; for example a straw boater hat, and a type of military short, cylindrical type of hat. I don't know why the Driver's cap is called a cheese cutter, but these last two often may have chin straps, which might cut into the chin.