| Noun | 1. | downhill - the downward slope of a hill | |
| 2. | downhill - a ski race down a trail | |
| Adj. | 1. | downhill - sloping down rather steeply | |
| Adv. | 1. | downhill - toward a lower or inferior state; "your performance has been going downhill for a long time now" | |
| 2. | downhill - toward the bottom of a hill; "running downhill, he gained a lot of speed" | |