größeren
größeren is not a standalone word in German but the inflected form of the adjective größer, the comparative of groß. It appears before a noun according to German adjective declension and is most common with plural nouns or in singular phrases where the determiner requires the ending -en (weak or mixed declension).
In the plural after a definite determiner, größeren appears as in Die größeren Städte wachsen schnell. It
größeren derives from größer, the comparative form of groß, with typical German umlaut and the -en ending
groß, größer, German declension, comparative forms in German.