noun, feminine/monˌtaɲa ˈrusa/plural: montañas rusas
rollercoaster; Used other than figuratively or idiomatically: see montaña, ruso.
“Chela gritó, “¡Vamos a la montaña rusa! ¡Qué divertido!” — Chela screamed, "Let's go to the rollercoaster! How fun!
Literally, “Russian mountain”, a singular calque of French montagnes russes, which see for more.