the.com/rollercoaster

means A rollercoaster is an amusement-park ride in which cars travel along a steep, twisting track at high speed, delivering deliberate drops, loops, and lurches for the thrill of it; figuratively, any experience full of abrupt emotional ups and downs.

from A plain compound of 'roller' and 'coaster' — the cars 'coast' downhill on rollers or wheels. The ride's ancestor is often traced to the 'Russian Mountains,' towering ice-covered slides enjoyed in 18th-century Russia, where riders shot down on sleds; the French, importing the idea, called such attractions 'montagnes russes' (a name still used in French today). The American 'roller coaster' name took hold in the late 19th century as gravity-powered scenic and switchback railways spread, and 'coaster' here carries its old sense of moving freely under momentum, no engine required.