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