www.alphadictionary.com

(From Wikipedia) "A ferrule (a corruption of Latin viriola "small bracelet", under the influence of ferrum "iron") is any of a number of types of objects, generally used for fastening, joining, sealing or reinforcement."

Thought this interesting...

I'll second this. I'm surprised it hasn't already been done. How else are people going to know what the thing on the pointed end of an umbrella is?