i'm pretty sure it's a made up word, taking "de" from latin languages, meaning of or relating to, and culture, meaning:obvious. so the combined meaning would be something of or relating to culture; cultured. thats my best guess anyways.
also, ranka is 1/4 zentradi, right? so how did that happen? it means ONE OF HER GRANDPARENTS FUCKED A GIANT. think about it. what are the implications of that?