When dictionaries say that a noun is uncountable, it describes the common usage, and is not an absolute rule. Money/water/bread, etc, can have plural forms, but they are not the most common forms of the noun. If you walk into a bank and say that you want ten monies, you probably won't get a satisfactory result. However, that doesn't means that these words can never ever have a plural form. It also doesn't mean that the dictionaries are wrong- more detailed dictionaries have the space to break down all the possible uses, but shorter dictionaries tend to give the most common. The more definitive and precise an answer you want from a dictionary, the bigger and more authoritative a dictionary you should use.