What is the Greek word that means seller of used books?

There isn't a single, established Greek word that precisely means "seller of used books." You'd have to use a descriptive phrase. Options include:

* πωλητής μεταχειρισμένων βιβλίων (politēs metacheirismenōn bibliōn): This translates literally to "seller of used books." It's straightforward and easily understood.

* βιβλιοπώλης μεταχειρισμένων (bibliopōlēs metacheirismenōn): This means "used book seller," using the word *bibliopōlēs* (bookseller) and modifying it.

The first option is probably more common and easier to understand for a native Greek speaker.