Definition: The term bell curve is used to describe the mathematical concept called normal distribution, sometimes referred to as Gaussian distribution. âBell curveâ refers to the shape that is created when a line is plotted using the data points for an item that meets the criteria of ânormal distributionâ.he important things to note about a normal distribution is the curve is concentrated in the center and decreases on either side. This is significant in that the data has less of a tendency to produce unusually extreme values, called outliers, as compared to other distributions.