De or het vlakornament?

The correct Dutch article is:

het vlakornament

Rule Words ending in -ment: usually het. See the rule
Meaning (Dutch) (bouwkunde) vlak uitgevoerd ornament

How to use vlakornament

the vlakornamenthet vlakornament
this vlakornamentdit vlakornament
that vlakornamentdat vlakornament
our vlakornamentons vlakornament
your vlakornamentjouw vlakornament
every vlakornamentelk vlakornament
which vlakornament?welk vlakornament?
a big vlakornament / the big vlakornamenteen groot vlakornament, het grote vlakornament

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