Multiple synonym per search term

I had to define multiple synonyms per search term, to do so here the procedure:

1. Go into your site’s frontend and search each search term you want to add a synonym for.
2. Log into your site’s backend and navigate to Reports > Search Terms and look for the search terms you typed in the frontend
3. Clicking on the search term will allow you to edit the term itself, there you can specify “Synonym for”, that is exactly what you need to define that search term as synonym for your “main” search term.

Enjoy!