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