from
The Collaborative International Dictionary of English v.0.48
Ferrule \Fer"rule\ (f[e^]r"r[i^]l or f[e^]r"r[.u]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.
[1913 Webster]
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.
[PJC]
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.
[1913 Webster]
4. Hence: (Chemistry) A bushing used at the joints of metal
tubing in HPLC equipment to make a tight seal.
[PJC]
5. (Fishing) One of several small rings at the top of a
casting rod which holds the fishing line. --RHUD
[PJC]