FWVGA is an abbreviation for Full Wide Video Graphics Array which refers to a display resolution of 854x480 pixels.
854x480 is approximately the 16:9 aspect ratio of anamorphically "un-squeezed" NTSC DVD widescreen video and considered a "safe" resolution that does not crop any of the image.
It is called Full WVGA to distinguish it from other, narrower WVGA resolutions which require cropping 16:9 aspect ratio high-definition video (i.e. it is full width, albeit with considerable reduction in size).
Since a pixel must be a whole number, rounding up to 854 ensures inclusion of the entire image.
The following is a list of smartphones which incorporate FWVGA displays.