Just to be a bit pedantic I say that every camera, regardless of format or medium, is a full frame camera in that it will expose it's entire sensor, or dedicated area of film, at every exposure.
However the term full frame, has more currently come to mean the difference between a 135 format sized sensor (size of a traditional 35 mm SLR exposure) and a smaller, like P&S or APS-C size, sensor. For example a Nikon FX format camera has a sensor that is about 42 mm in the diagonal compared to a DX format Nikon which has a sensor of about a 28 mm in the diagonal. The FX is said to be full frame while the DX is said to be cropped.
edit: Olympus had a film camera that was 'half frame' in that it used regular 35mm film but the camera exposed an area only half as big as a regular 35mm slr. So the camera got twice as many exposures on a roll (portrait orientation) as a regular 35 mm slr. Also, some digital backs for MF cameras have a sensor size somewhat smaller than their film backs, so these could be said to be 'cropped' as well even if their sensors are bigger than 42mm in diagonal.