How do you define leadership?

A process of social influence in which one person can enlist the aid and support of others in the accomplishment of a common task is leadership.
In other word organizing a group of people to achieve a common goal is leadership.

Leadership has nothing to do with seniority or one’s position in the hierarchy of a company Leadership has nothing to do with titles.
Leadership isn’t management.
This is the big one.
Leadership and management are not synonymous.
You have15 people in your down-line and P&L responsibility? Good for you, hopefully you are a good manager.
Good management is needed.
Managers need to plan, measure, monitor, coordinate, solve, hire, fire, and so many other things.
Typically, managers manage things.
Leaders lead people.