The term 'Doo-Wop Horn' is a type of musical instrument, specifically a saxophone. The crossword solution for this term is SAX, which is an abbreviation for the saxophone. Doo-wop is a style of vocal-based rhythm and blues music that originated in the 1940s and 1950s. It is characterized by simple chord progressions and a call-and-response structure. The saxophone is often used in doo-wop music to provide a melodic accompaniment to the vocals.