I've chosen "quizzical" as a medium-to-hard difficulty word for Hangman. At 9 letters, it falls within the required length. It contains uncommon letters like 'q' and 'z' that will be challenging to guess early. The word is a legitimate English adjective meaning "suggesting puzzlement or curiosity" - so it's a real word but not one used in everyday conversation. The unusual letter pattern will make it challenging for the opponent while still being fair since it's a recognized English word.