Hub (noun)

1. The central part of a wheel around which the wheel turns.
2. A center of activity or connection, especially a place where several lines of transportation meet.
3. The main or central part of an object or system.

Origin:

Derived from the old english word hybbe, meaning 'centre, wheel-spindle, hub of a wheel'.

Examples:

1. The airport is a hub for several airlines.
2. The city has become a hub for start-ups in recent years.
3. The wheel's hub is the part that attaches to the axle.
4. The hub of the bicycle wheel was the most important component.
5. The company has become a hub for innovative technologies.