What's the plural form of heterosuggestion? Here's the word you're looking for.
Answer
The noun heterosuggestion can be countable or uncountable.
In more general, commonly used, contexts, the plural form will also be heterosuggestion.
However, in more specific contexts, the plural form can also be heterosuggestions e.g. in reference to various types of heterosuggestions
or a collection of heterosuggestions.
Examples
I find in such cases autosuggestion more liberating than heterosuggestion if the development has not gone too far.