capital

A capital is the most important city of a country. The government of the country is usually located there.

The (field) capital is the most important city in that particular field.

Example: Hollywood is the film capital, New York the theater capital, Las Vegas the gambling capital.

A person's capital is all his money and wealth.

A capital forms the topmost member of a column or pilaster. It broadens the area of the column's supporting surface.

A capital object or idea is something that is very important.