Secondhand/antique book shops in Lisbon

I am soon going to Lisbon. Being a big enthusiast of dictionaries, I would like to acquire some when I get there. What I am mostly interested in are big technical (but not only) dictionaries at a discount or used ones, even slightly outdated.

Where in the broadly understood city center could I find them? In my country we have plenty of shops dedicated to second hand books everywhere, but I don't know if they function as a separate thing in Portugal. What would be the name of such establishments to google?

Also, I do not speak Portuguese (might be a factor).

I would be grateful for any specific or generic hints you could provide me with regarding this issue :)