Meister
The German word Meister means master, and in English is used as a suffix. Adding this to the end of an English word describes someone who has expert knowledge or proficiency in that field, possibly dominating it with their outstanding skill. There is no established convention yet in English about treating the new word as a single compound word, or hyphenating it, or writing two separate words.
The German word Meister is possibly a bit broader in meaning than the English word master, comprising also accredited craftsmen (who are a key element in Germany’s Mittelstand), master artists, and also describing a winner or champion. A Weltmeister is a world champion, and a Weltmeisterschaft is a world championship.