If a fewtrer is a worker in felt, and a fewterer is a keeper of greyhounds, what does the verb to fewter mean?
Well, it can mean two things, though sadly neither of them is anything to do with greyhounds. To fewter can mean to pack together (presumably because you make felt by squashing wool into a mat) and it also means to put a lance into its rest. The inside of a lance-rest, you see, is lined with felt.
Yes, yes, I know, that's of absolutely no use whatsoever to more or less everybody.
But then the useless information is so often the best.
photo by Pseudopanax 2013, Harcourt Park, Upper Hutt*
Thing To Dream About Doing Today: fewter. This word comes from the Old French feutre, filter or felt, from the Latin filtrum, filter.
The word fewterer is, sadly, nothing to do with any of this. The word comes from the Latin vertragum, greyhound.
*No, I can see a lance rest, either. Still, you get the general idea.