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