[fer-uh
l, -ool] 
noun, verb, -ruled, -rul⋅ing.| 1. | a ring or cap, usually of metal, put around the end of a post, cane, or the like, to prevent splitting. |
| 2. | a short metal sleeve for strengthening a tool handle at the end holding the tool. |
| 3. | a bushing or adapter holding the end of a tube and inserted into a hole in a plate in order to make a tight fit, used in boilers, condensers, etc. |
| 4. | a short ring for reinforcing or decreasing the interior diameter of the end of a tube. |
| 5. | a short plumbing fitting, covered at its outer end and caulked or otherwise fixed to a branch from a pipe so that it can be removed to give access to the interior of the pipe. |
| 6. | Angling.
|
| 7. | to furnish with a ferrule. |
fer·rule (fěr'əl)  (click for larger image in new window) n.
[Alteration (influenced by Latin ferrum, iron) of Middle English verrele, from Old French virole, from Latin viriola, little bracelet, diminutive of viriae, bracelets; see wei- in Indo-European roots.] fer'rule v. |