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