What's the plural form of rheumatiz? Here's the word you're looking for.
Answer
The noun rheumatiz can be countable or uncountable.
In more general, commonly used, contexts, the plural form will also be rheumatiz.
However, in more specific contexts, the plural form can also be rheumatizes e.g. in reference to various types of rheumatizes
or a collection of rheumatizes.
Examples
Hain't had the rheumatiz, nor shakin' ager, nor any of that buzzing in your head?