wide angle lens question

I want to get a wide angle lens for a Fuji FinePix S5200 I recently purchased, but I am puzzled about something. When the description of a lens is given, what is meant by 55mm or 52mm, etc.? I assume it is the size of the lens or the thread type. I think adapters can be used but I don't want to buy something and then find I cannot use it.

Please enlighten me.

Thanks!

 

I think it means thread size. On the camera it might (and hopefully will) have the thead size written round the outside of the lens. It does on my JVC, which is how I knew what size adapter to buy off ebay.

 

Thanks. I sort of thought that but wanted to be sure.

 

Easy way to do it... Find what you want on e-bay, then go to a camera shop, with your camera, ask to fit it, and try out what you are considering buying. If it works...