The term CIRCUS SOUND can be broken down into four crossword solutions: OOH (3 letters), ROAR (4 letters), ROARS (5 letters), and RING (4 letters). OOH is a sound often made to express surprise or admiration, while ROAR is a loud, deep sound made by a lion or other large animal. ROARS is the plural form of ROAR, and RING is a sound made by a bell or other metal object when struck. All of these sounds are commonly heard in a circus, making them appropriate answers for this crossword puzzle.