"Developer preview" refers to a version of a software or platform that is released by its developers for other software developers to test and provide input before it is made available to the general public. Full definition
Now that the first developer preview of Android P is here, it's time to look ahead to see where we go next. (androidcentral.com)
Adaptive icons were noticed in the second developer preview for Android O and they will eventually make it to a number of apps on smartphones. (news.softpedia.com)
The feature reportedly can not be disabled in the first developer preview of the new Android build, though there are still no guarantees it will make it to the stable channel. (androidheadlines.com)