FFX-Format
Refers to Nikon cameras that feature a 35mm film-frame size sensor. Nikon digital SLRs have either an FX or a DX sensor. The FX sensor, measuring 23.9 x 36mm, is roughly equivalent to the size of the 35mm film frame. The DX sensor is smaller, measuring 15.8 x 23.6mm. The FX sensor, with more "light gathering" area, offers higher sensitivity and, generally, lower noise. There is, of course, no crop factor present with the FX sensor.
To read more about the FX-Format, click here.