Ferrule does not really mean anything but in fact it is a name given to different kinds of metal objects. It is basically a circular clamp that manages to cling together and also has some kind of attached fibers, wires or posts. Some of the most well used examples are a brush, an ice axe and a metal ring.
In a brush the ferrule is what holds the bristles or the hair of the brush together. In an ice axe the ferrule is the metal spike that is at the end of the shaft. And a metal ring is usually referred to a curly kind of thing that holds the eraser well tight in its place or even with a pencil that ahs an attached rubber. A ferrule is also referred to a metal cap that is placed at the end of a bicycle's cable housing.
In a brush the ferrule is what holds the bristles or the hair of the brush together. In an ice axe the ferrule is the metal spike that is at the end of the shaft. And a metal ring is usually referred to a curly kind of thing that holds the eraser well tight in its place or even with a pencil that ahs an attached rubber. A ferrule is also referred to a metal cap that is placed at the end of a bicycle's cable housing.