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