"Fresh install" refers to the process of completely removing all existing software and data from a computer or device, and then installing a new or updated version of the operating system or software. Full definition
It's not only useful for upgrades, but is also super handy when it comes to fresh installing of Windows. (redmondpie.com)
If you have the app already downloaded it will continue to work for the foreseeable future, but it will no longer be available for fresh installs if you delete it or buy a new device. (goodereader.com)
The January Security Bulletin also ships with small functional improvements involving over-the-air update performance after fresh installs, and a tweak in Android's keystore key upgrade behavior. (xda-developers.com)