Ferrule
Ferrule (fer"ril or fer"rul; 277) , noun
[Formerly verrel, French virole, from Latin viriola little bracelet, dim. of viriae, pl., bracelets; prob. akin to viere to twist, weave, and English withe. The spelling with f is due to confusion with Latin ferrum iron.]
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.
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.
3.
(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.
4.
(Chemistry) A bushing used at the joints of metal tubing in HPLC equipment to make a tight seal.
5.
(Fishing) One of several small rings at the top of a casting rod which holds the fishing line. — RHUD