In one of the recent past puzzles, I tried Lieder. Which was promptly flagged as "unknown".
Finding that it wasn't even the rare word list puzzled me.
For those unfamiliar with the term, Lieder are the result of using a poem as the lyrics for a song with a classical music score. As the name suggests, they're most often thought of as German musical compositions, and indeed, the majority of extant Lieder are the products of German composers (Schumann was a particularly prolific composer of Lieder, with Schubert also being particularly associated with this genre Death and the Maiden being a possibly canonical example, followed by Richard Strauss, Brahms and Beethoven).
I admit that the term probably wouldn't have occurred to many people, but might have been in the minds of players with some background in classical music. I'm therefore surprised to find it not present even in the rare word list.
