mean^{3} (miːn)  
—n  
1.  the middle point, state, or course between limits or extremes 
2.  moderation 
3.  maths 
a. the second and third terms of a proportion, as b and c in a/b = c/d  
b. another name for average See also geometric mean  
4.  statistics a statistic obtained by multiplying each possible value of a variable by its probability and then taking the sum or integral over the range of the variable 
—adj  
5.  intermediate or medium in size, quantity, etc 
6.  occurring halfway between extremes or limits; average 
[C14: via AngloNorman from Old French moien, from Late Latin mediānus 
mean (mēn)
n.
Something having a position, quality, or condition midway between extremes; a medium.
A number that typifies a set of numbers, such as a geometric mean or an arithmetic mean.
The average value of a set of numbers.
Occupying a middle or intermediate position between two extremes.
Intermediate in size, extent, quality, time, or degree; medium.
mean (mēn) Pronunciation Key

An average in statistics. (See under “Physical Sciences and Mathematics.”)
In statistics, an average of a group of numbers or data points. With a group of numbers, the mean is obtained by adding them and dividing by the number of numbers in the group. Thus the mean of five, seven, and twelve is eight (twentyfour divided by three). (Compare median and mode.)