An upright instrument is a type of musical instrument that stands vertically on the floor. The two most common examples are the PIANO and the BASS. The PIANO is a five-letter word and the BASS is a four-letter word. Both instruments have a long history and are used in many different genres of music. The PIANO is a keyboard instrument with a range of notes and tones, while the BASS is a stringed instrument with a deep, resonant sound.