How to add additional search terms (e.g. synonyms) to the search?

I’m running a blog about different software tools. I frequently use the search to find articles that I wrote for the blog. I also wrote an article about latexdiff, but always forget the name and try for example difftex which gives no results in the search.

I thought, that adding a tag difftex might solve the problem, without disturbing the main article by adding e.g. a sentence “I sometimes mix it up with difftex, difflatex,…”.

But I found out, that tags are not used for the search. What is the golden way to add terms to the search?

I think your question has already been asked. You can add additional terms as post tags, and then these tags can be added to the search query via filters. See answer.