Pure acid without water?

Sure, all acids can be pure. For example, HCl is a gas in its pure state, no water. Another is H2SO4, it is a liquid at 100% purity.

So an acid is defined in its ability to deliver an H+ (or a proton). It does not mean all of the H+ is present in its ionized form. You have to add water for that to happen and the acid can then provide the H+ to the added water. This property is used in a practical sense in industry. High purity sulfuric acid (>98%) is often stored in plain steel tanks because there is so little water to ionize the H+, it is not corrosive. But 4% H2SO4? You have to use stainless steel or some other high alloy to prevent it from being corroded by the acid, plenty of H+ there.

There are acids (proton donors) that do not require water, in fact, they have to be used in an anhydrous medium; they are called superacids:

http://en.wikipedia.org/wiki/Superacid