A ramp is a slope or an incline, a surface that tilts from one level to another. Someone using a wheelchair might need a ramp to get from the doorway of a building down to its parking lot.
A skateboarder might use a ramp to gather speed, while a man pushing a stroller uses it to push his baby onto the sidewalk after crossing the street. Passengers also walk down ramps when they exit boats and trains. There's also the plant called a ramp, also known as wild onion or wild garlic. As a verb, to ramp means to provide with a ramp, but the more common "to ramp up" means "to increase."