ferrule

thumb|A wire rope terminated with a ferrule (left) and a thimble (right) thumb|upright|Zuffolo | Picco pipe with nickel silver ferrule thumb|right|upright=1.5|Non-circular ferrules holding bristles of a brush to its handle

A ferrule (a corruption of Latin ' "small bracelet", under the influence of ' "iron") is any of a number of types of objects, generally used for fastening, joining, sealing, or reinforcement. They are often narrow circular rings made from metal, or less commonly, plastic. Ferrules are also often referred to as eyelets or grommets within the manufacturing industry.