What is the meaning of -inen?

Creates adjectives:

1. Creates adjectives signifying a certain quality: -like, -ous, -y

   Creates adjectives signifying a certain quality: -like, -ous, -y

   Creates adjectives indicating a material of which something is made: -en

   Creates adjectives from present active participles, indicating a tendency to be/do something.

   Creates adjectives from foreign roots: -ic

   Source: wiktionary.org