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