1. the central part of a car wheel (or fan or propeller etc) through which the shaft or axle passes

Definition categories: man–made, part, portion

2. a center of activity or interest or commerce or transportation; a focal point around which events revolve

- the playground is the hub of parental supervision

- the airport is the economic hub of the area

Definition categories: location, center, centre, eye, heart, middle

Sentences with hub as a noun:

- Hongkong airport is one of the most important air traffic hubs in Asia.

- a hub in the road