[statistics] also bell-shaped normal curve , or bell-shaped distribution . when the class width in a histogram become sufficiently small, the frequency polygon may be approximated by a smooth curve, that is, the normal curve .
Note: most common normal curve is mesokurtic (normal) distribution; if the curve has a sharp peak, it has a leptokurtic (peaky) distribution; if the curve is relatively flat, it has a platykurtic (flat) distribution.