roll·er coast·er 
/ˈroʊlɚˌkoʊstɚ/ noun
plural ∼ -ers /ˈroʊlɚˌkoʊstɚ/ noun [count] 1 : a ride at an amusement park which is like a small, open train with tracks that are high off the ground and that have sharp curves and steep hills
▪ We went for a ride on the roller coaster. ▪ a roller-coaster ride 2 : a situation or experience that involves sudden and extreme changes
▪ The divorce was an emotional roller coaster for both of them. ▪ He's had a roller-coaster career. [=a career with many ups and downs]
▪ We went for a ride on the roller coaster. ▪ a roller-coaster ride
▪ The divorce was an emotional roller coaster for both of them. ▪ He's had a roller-coaster career. [=a career with many ups and downs]
