Definition of downhilling in English:

downhilling

Pronunciation /ˌdaʊnˈhɪlɪŋ/ /ˈdaʊnhɪlɪŋ/

noun

  • The action of travelling at high speed down a steep slope on a toboggan, skis, a mountain bike, etc.; this as a recreation or sport; downhill racing.

Origin

Late 19th century; earliest use found in The Bismarck Tribune. From downhill + -ing.