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