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