De or het wintercompetitie?

The correct Dutch article is:

de wintercompetitie

Rule Words ending in -tie and -sie: almost always de. See the rule

How to use wintercompetitie

the wintercompetitiede wintercompetitie
this wintercompetitiedeze wintercompetitie
that wintercompetitiedie wintercompetitie
our wintercompetitieonze wintercompetitie
your wintercompetitiejouw wintercompetitie
every wintercompetitieelke wintercompetitie
which wintercompetitie?welke wintercompetitie?
a big wintercompetitie / the big wintercompetitieeen grote wintercompetitie, de grote wintercompetitie