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