roller coaster roller coaster /ˈroʊlər koʊstər/

noun

1. Elevated railway in an amusement park (usually with sharp curves and steep inclines)  ( big dipper , chute-the-chute , roller coaster )
   elevated railway in an amusement park (usually with sharp curves and steep inclines)
    The roller coaster was a thrilling ride that left my heart racing
   The roller coaster was a thrilling ride that left my heart racing
   
   
2. Anything characterized by abrupt and extreme changes (especially up and down)  ( roller coaster )
   anything characterized by abrupt and extreme changes (especially up and down)
    The economy has been on a roller coaster all year
   the economy has been on a roller coaster all year