I. down ‧ hill 1 /ˌdaʊnˈhɪl◂/ BrE AmE adverb
1 . towards the bottom of a hill or towards lower land OPP uphill :
I was going downhill and my brakes failed.
2 . go downhill if a situation goes downhill, it gets worse SYN deteriorate :
Grandma fell and broke her leg, and she went downhill quite rapidly after that.
II. downhill 2 BrE AmE adjective
1 . on a slope that goes down to a lower point OPP uphill :
downhill skiing
It’s a long walk back, but at least it’s all downhill.
2 . be all downhill (from here)/be downhill all the way (from here) to be easy to do, because you have already done the hard part:
The worst is over – it’s all downhill from here.