Android Silver is thought to be Google's new version of its Google Play edition handsets. While it's still a rumour it's looking more likely as Google Play edition handsets start to vanish from the Play Store.
Google Play Edition handsets are made by third parties but come with the pure Android operating system. The HTC One (M7), Sony Z Ultra and LG G Pad, have all recently vanished from the Store.
Android Silver, unlike Google Play, is thought to outline the hardware specifics of handsets. A bit like Intel does with its ultrabook guidelines.
Android Silver is rumoured to arrive in 2015, but with space being made on the Google Play Store perhaps they will arrive sooner. There's certainly no rumours of a Samsung Galaxy S5 Google Play Edition handset yet.
The Nexus 6 smartphone is still expected to be launched this year.