There's no single Greek word "den". It's possible you're thinking of a word from another language, or perhaps a misspelling of a Greek word. Could you provide more context? For example:
* What is the word referring to? (e.g., a place, a concept, a thing)
* Where did you encounter this word? (e.g., a book, a website, a conversation)
With more information, I might be able to help you figure out what word you mean.