(adjective)
meant to be used while sitting on a horse's back and controlling its movements, or otherwise relating to this action;
e.g. She was wearing riding clothes for her journey.
(verb)
sitting on the back of an animal such as a horse or a vehicle such as a bicycle or a motorcycle and controlling its movements for recreation, traveling, or sport;
e.g. They were riding much faster than I was, so they were far ahead of me on the trail. She likes riding her bike early in the morning.
(verb)
(American) traveling in a vehicle such as a car or a bus as a passenger;
e.g. He has been riding the bus to work since his car broke down.
(verb)
being supported and/or carried by something that has a lot of force or momentum;
e.g. We saw a surfer riding a giant wave toward the beach.