First, to begin, I'm a hobbyist with no formal background whatsoever in Latin. I only know what I can manage to successfully google and read on my own.
Anyway, I've read that Latin can't use nouns as adjectives. So if you want to say a word like, 'chicken soup,' then you would likely need to place the word chicken into the genitive case or create an adjective and use this word instead.
But while looking up words on Wiktionary I came across this entry, dēfēnsor cīvitātis.
I swear, that's just two nouns back to back. Can anyone explain what I'm seeing and what rule of Latin grammar I'm missing?