What does CAT stand for in an AUDI A8 1995?

I have this indicator flashing for the whole time. We havent used the car for 4 years and now we are fixing it up. The CAT indicator keeps flashing and the car keeps having a vibrate when its in place(not accelerated) Help please? I just want to know what CAT is... Can it be the Catalytic Converter? or does it not have one...? Please help!!!