This use case demonstrates how you can use the page property macro set to ‘hidden' to specify page keywords. When you insert certain words via the hidden page property macro then you can make the page come up with that when you search for that word, without having to specify the keyword on the page visually.

Have a look at the edit mode to see the hidden page property macro on this page with a keyword that otherwise doesn’t appear on this page. You can search for that keyword in Confluence and this page still comes up.