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