RhymeZone: fettler definitions

Definitions of fettler:

noun: A person who maintains railway lines.
noun: Someone whose job is to sand and grind small imperfections from metal and ceramic castings.
noun: (by extension) Someone who fiddles or tinkers with things.
noun: (slang, UK, Lancashire) A friend or mate
noun: (mining, historical) An ostler; one who looks after the horses in a mine.

(Definitions from Wiktionary)