As part of a Soapbox update on September 10, 2015, the Salesforce Search app was renamed Directories. This change was made in conjunction with renaming the Salesforce Submit app to Forms. These changes were made for concision, to provide a more descriptive name for the apps, and to bring consistency to our naming conventions from both a product and marketing perspective.
So, not to worry! You still have your Salesforce Search app with all of its features! It just has a shorter name!