Definition of Fractional share
Unit of stock less than a full share. This term comes into use with a stock dividend in an instance for example where an owner of 75 shares receives a 10% stock dividend. That part or portion of a share of stock indicated on a right or warrant as subject to purchase by the exercise of such right.
That's the definition of Fractional share in Black's Law Dictionary 6th Edition. Courtesy of Cekhukum.com.