hölzernen
Hölzernen is the inflected form of the German adjective hölzern, meaning wooden. It functions as an attributive adjective that agrees with a noun in gender, number, and case. The form hölzernen appears in certain grammatical contexts, most commonly in the dative plural and in other cases when the determiner requires a stronger or mixed ending.
In practice, hölzernen is heard and written in phrases such as die hölzernen Möbel (the wooden furniture)
Because hölzern is a normal German adjective, hölzernen is not a separate noun and does not appear
See also: German adjective declension, hölzern, wood in German vocabulary.