Leadership defined

I've been looking for a good definition of leadership for a long time. Some argue that you need to have followers to be a leader and some say that leadership is influence, others mention authority together with leadership or want to give the leader the ability to tell people what to do.
When I read 'Becoming a Technical Leader' by Gerald M. Weinberg I found a definition that fits perfectly in with my own views and thoughts on what kind of leader I want to become:

"Leadership is the process of creating an environment in which people become empowered"