De or het hydraulica?

The correct Dutch article is:

de hydraulica

Rule Words ending in -ica: usually de. See the rule
Meaning (Dutch) (natuurkunde) de leer van de vloeistoffen, omvattende de hydrostatica en de hydrodynamica

How to use hydraulica

the hydraulicade hydraulica
this hydraulicadeze hydraulica
that hydraulicadie hydraulica
our hydraulicaonze hydraulica
your hydraulicajouw hydraulica
every hydraulicaelke hydraulica
which hydraulica?welke hydraulica?
a big hydraulica / the big hydraulicaeen grote hydraulica, de grote hydraulica

Meaning, plural, diminutive, pronunciation and translations: WikiWoordenboek (Dutch Wiktionary) (CC BY-SA 4.0). Example sentences: Tatoeba (CC BY 2.0 FR).