De or het themazitting?

The correct Dutch article is:

de themazitting

Rule Words ending in -ing: almost always de. See the rule

How to use themazitting

the themazittingde themazitting
this themazittingdeze themazitting
that themazittingdie themazitting
our themazittingonze themazitting
your themazittingjouw themazitting
every themazittingelke themazitting
which themazitting?welke themazitting?
a big themazitting / the big themazittingeen grote themazitting, de grote themazitting