This is the 2205th most frequent Dutch word.
miljardair
Billionaire.
Here 'miljardair' is used as a noun to indicate a person with significant wealth, specifically a billionaire.
De miljardair gaf miljoenen aan liefdadigheid.
The billionaire donated millions to charity.
In this sentence, 'miljardair' describes the owner of the house, again used as a noun to denote a billionaire.
Het huis van de miljardair was enorm en luxueus.
The house of the billionaire was enormous and luxurious.
Here, 'miljardair' is used to highlight the exclusivity and wealth required to own the car in question.