Definition of Fractional
As applied to tracts of land, particularly townships, sections, quarter sections, and other divisions according to the government survey, and also mining claims, this term means that the exterior boundary lines are laid down to include the whole of such a division or such a claim, but that the tract in question does not measure up to the full extent or include the whole acreage, because a portion of it is cut off by an overlapping survey, a river or lake, or some other external interference. Any irregular division whether containing more or less than conventional amount of acreage
That's the definition of Fractional in Black's Law Dictionary 6th Edition. Courtesy of Cekhukum.com.