Recently, I was working on a custom search for a project and received the complaint that it wasn’t pulling up the proper results. They were searching “Procedure” and nothing with ProcedureS in the document was coming up. Shouldn’t SharePoint be smart enough to pull up different forms of a word? I thought so and so did the users of the site. When I started researching why it wasn’t pulling up plural words, I found that it was a very simple solution. I’m not sure why SharePoint doesn’t do this by default but you just have to change a setting on the search results page.
Under the Results Query Options, be sure to check the “Enable Search Term Stemming” option. This will solve that problem. Hope this helps someone.