What's the plural form of waggonage? Here's the word you're looking for.
Answer
The noun waggonage can be countable or uncountable.
In more general, commonly used, contexts, the plural form will also be waggonage.
However, in more specific contexts, the plural form can also be waggonages e.g. in reference to various types of waggonages
or a collection of waggonages.