ferrule

n metal ring or cap placed on the end of a stick, an umbrella, etc to stop it splitting or wearing down （手杖、 伞等顶端的）金属箍, 金属包头.

femur, fen, fence, fencer, fencing, fend, fender, fennel, feral, ferment, fermentation, fern, ferny, ferocious, ferociously, ferocity, ferret, Ferris wheel, ferroconcrete, ferrous, ferry, ferry-boat, ferryboat, ferryman, fertile, fertility, fertilization, fertilisation, fertilize, fertilize, fertilise, fertilizer, fertilizer, fertiliser, fervent, fervently, fervid, fervidly, fervor, fervour (US fervor), festal, fester, festival,