A measure of the average of a set of data, calculated by adding up all terms and dividing by the number of terms in the set. For example the mean of 3, 5, and 13 is the numbers added together (21) divided by the amount of numbers (3) which works out as 7.
The mean takes account of all values and finds the overall average. Finding the mean is the most common way of measuring a data set's average, but can be problematic if one or two anomalous (wrong) values are taken and skew the result.