Slope is the steepness of something that goes up or down at an angle. A gentle slope might be easy to walk up, like a slightly tilted driveway, while a steep slope could make you work hard climbing, like a ski run plunging down a mountain. Hills have slopes, wheelchair ramps have slopes, and even a book leaning against a wall creates a slope.

In mathematics, slope measures how much something rises or falls as you move across it. If you graph a line on paper, its slope tells you whether it climbs sharply upward, descends steeply downward, or stays relatively flat. A horizontal line has a slope of zero. Mathematicians calculate slope by comparing how far up or down something goes to how far across it goes. A line that rises three units for every one unit it moves right has a steeper slope than one that rises only one unit.

The word can also mean to tilt or slant. A roof slopes downward so rain slides off. A child's handwriting might slope to the right as they write faster. Skiers love to hit the slopes, meaning they're heading out to ski down snow-covered mountainsides. When something goes downhill quickly, people say it's a slippery slope, warning that one small problem might lead to bigger ones.