The act, manner, or power of flying, either with or without wings. Humans have dreamed of being able to fly for thousands of years, and have only developed the science of flight in the previous century, with the airplane and the rocket.
Many animals, including birds, insects, and bats, are able to fly -- we envy them because they can enjoy the freedom of flight without having to bother with airports, security checkpoints, carry-on luggage, and in-flight movies.