A moped is a small, light two-wheel vehicle with a little engine, slower and weaker than a motorcycle. The old ones even had bicycle pedals, so you could start by pedalling and then let the engine take over. In many countries a moped is its own legal class: you may ride one younger, or without a full motorbike licence, because it cannot go very fast. In towns it is a cheap practical runabout, not a racing bike. It is countable: a moped, two mopeds. Though actually, people sometimes stretch the word to any small scooter, even when the pedals are long gone. And the same spelling is the past of mope — yesterday he moped in his room — which is a completely different word.