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