Where in Jordan can I find cheap second-hand book stores that sell dictionaries and other language materials?

The good news - Jordan and particularly Amman have seen a huge increase in the number of students coming to learn Arabic (particularly since Damascus and Cairo became less desirable locations...), so there's a growing amount of material available for people interested in languages.

Cheap?

The bad news is, it tends not to be cheap and second-hand language related books are often quickly hoovered up by incoming students and tend to be sold person-to-person at language schools or via social media. There aren't many places to buy second hand books that I'm aware of that are likely to be of the right type:

• Souk Jara is a very pleasant open-air market in downtown Amman near several popular tourist areas, has many stalls selling books, almost all in Arabic and mostly aimed at a local market but may be of some interest, and generally quite cheap including some second-hand book stalls
• The Amman Pasha Hotel has a book exchange of books in many languages. So, cheap, but they're probably mostly pulpy holiday books left behind by guests. But you might get lucky.

I've seen a few small second hand books / bric-a-brac shops but they understandably mostly sell things along the lines of religious texts and Arabic-language accountancy course books from 1995.

In many languages?

So you might need to compromise on the "cheap" part. There are plenty of large bookshops that have language-related materials and sell books in multiple languages. Expect prices to be like an expensive European country (e.g. Scandinavia).

• Books@Cafe is well worth a visit. As well as being a well-stocked multi lingual (mostly English and Arabic) modern book shop, it is also a very nice cafe and restaurant with views over central Amman. It's not far from Souk Jara and the Rainbow Street area.
• The Good Bookshop is also in the same area. Not been but it's well regarded.
• There are many more but you'll find as much info on various listings pages (example) as I could give. Most large shopping malls contain a bookshop with books in English as well as Arabic (plus other languages, occasionally) and there's usually a small languages section.

Specifically about languages?

The question asked for bookshops rather than specific books, but something that might be of interest is that some of the Jordanian language schools and institutes have taken to printing and selling their own materials. This is because Jordanian Arabic (which is a branch of Levantine Arabic, which is a branch of colloquial Arabic aka Ammiya) has very little in the way of quality learning materials, so they've taken matters into their own hands.

One in particular is from Diwan Baladna, a small independent Arabic school / cultural institute. They have two books out which can be found in most large bookshops but would be very hard to find outside Jordan:

"The Unprecedented Spoken Arabic Dictionary" I imagine would be of interest to any curious person with an interest in languages. The main part is a huge compendium of idioms, with literal translations in English as well as the colloquial meaning, organised by theme, for example:

People (negative) - Selfish/Arrogant

• I tell him it's a bull, he says milk it. Said of the strong-headed person who asks for something that cannot be fulfilled and does not understand anything except what he desires.
• He limps in front of crippled ones. Said of the person who tries to display knowledge in front of those who have more knowledge than him.
• continues

The 'dictionary' part of the book is not of much use if you don't read Arabic script (there's no transliteration, but there is an audio CD), but the idioms are a great read even to non-Arabic-learners.

It might also be worth asking at some of the language schools. I don't know any through personal experience, but the French Institute is well regarded for Arabic (despite the name!).