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