Uphill means moving or sloping toward higher ground. When you ride your bike uphill, you're pedaling toward the top of a hill, which takes more effort than riding on flat ground or coasting downhill. A road that goes uphill climbs gradually or steeply toward higher elevation.

The word also describes any task that requires extra effort or faces serious obstacles. When a soccer team is losing 3-0 at halftime, they face an uphill battle to win the game. A student who missed two weeks of school has an uphill climb to catch up with the rest of the class. In this sense, uphill suggests that success is still possible but will require determination and hard work, just like reaching the top of a real hill requires pushing through the difficulty of the climb.

Notice that uphill is the opposite of downhill, which can mean physically descending or, figuratively, getting easier or worse. If things are going downhill, they're declining. If you're going uphill, you're working against gravity or circumstance, pushing toward something better.