What does miliardum mean in Latin?

miliardum, a noun, means “milliard (a short-scale billion)”.

What is the genitive of miliardum?

The genitive singular is miliardī. miliardum is neuter, second declension.

noun · neutersecond declension

miliardum n (genitive miliardī)

New Latinneutermilliard (a short-scale billion)
[…]cui miliarda 900 addenda erunt ad aedes instruendas, quae reditum circiter miliardorum centum quotannis praebebunt.1916, Alma roma: latinitatis praeconium singulis mensibus editum, page 177:
Pretio circiter tredecim miliardorum marcarum sexaginta quattuor aeroplana duorum motrorum ex nota F/A 18 Hornet acquirentur.1993, Latinankieliset uutiset, page 82: