Ferrule (f&ebreve_;rr&ibreve_;l or f&ebreve_;rr&usdot_;l; 277), n. [Formerly verrel, F. virole, fr. L. viriola little bracelet, dim. of viriae, pl., bracelets; prob. akin to viere to twist, weave, and E. withe. The spelling with f is due to confusion with L. ferrum iron.] [Sometimes spelled ferule.] 1. A ring or cap of metal put round a cane, tool, handle, or other similar object, to strengthen it, or prevent splitting and wearing.
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2. (Machinery) Any of various circular or cylindrical metal objects used at joints in a tube, pipe, or rod, especially to assist making a tight seal at a joint.
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3. Hence: (Steam Boilers) A bushing for expanding the end of a flue to fasten it tightly in the tube plate, or for partly filling up its mouth.
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4. Hence: (Chemistry) A bushing used at the joints of metal tubing in HPLC equipment to make a tight seal.
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5. (Fishing) One of several small rings at the top of a casting rod which holds the fishing line. RHUD
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