The term 'mouth-organ' is a colloquial name for a harmonica, which is a free-reed wind instrument. The crossword solutions for this term are UVULA (5 letters), TONGUE (6 letters), and HARMONICA (9 letters). The UVULA is a small fleshy extension at the back of the throat, while the TONGUE is a muscular organ in the mouth used for tasting, swallowing, and speaking. The harmonica is a type of mouth organ that is played by blowing air into it.