[ hʌɪ'pə:bələ ]
■ noun ( plural ~s or ~e -li: ) Mathematics a symmetrical open curve (or pair of curves) formed by the intersection of a cone (or pair of oppositely directed cones) with a plane at a smaller angle with its axis than the side of the cone.
Origin
C17: mod. L., from Gk huperbolē 'excess' (from huper 'above' + ballein 'to throw').