What is the term for the uniform increase or decrease in the width or diameter of a part?

The term that describes a uniform increase or decrease in the width or diameter of a part is known as taper. Tapering involves a gradual change along the length of an object, which can be applied to both cylindrical and conical shapes. This process is often used in manufacturing and machining to create parts that fit together more easily or to reduce weight.

In contrast, a fillet refers to a rounded corner on the edge of a part, typically used to improve strength or reduce stress concentrations. A bevel involves sloping or cutting off an edge or corner at an angle different from 90 degrees, often to create a finished edge on materials. A frustum is a three-dimensional shape created when a cone or pyramid is sliced parallel to its base, which does not describe a uniform change in diameter but rather a specific geometric form. Thus, taper is the correct term to identify the uniform change in dimensions.