De or het manisme?

The correct Dutch article is:

het manisme

Rule Words ending in -isme: almost always het. See the rule
Meaning (Dutch) de verering van de overledenen

How to use manisme

the manismehet manisme
this manismedit manisme
that manismedat manisme
our manismeons manisme
your manismejouw manisme
every manismeelk manisme
which manisme?welk manisme?
a big manisme / the big manismeeen groot manisme, het grote manisme

Dutch words ending in manisme

germanisme

In compound words, the last part decides the article. See the rule

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