The median is a type of average of a series of numbers.
For an odd number of numbers, the median is the number which is less than exactly half the other numbers (and therefore more than exactly half).
For an even number of numbers there is no one number that would be exactly half way down a list of the numbers ordered by size, so it is defined as halfway between the two middle numbers.
The median is often used to pick the "consensus" from financial forecasts. This is because an arithmetic mean would be distorted by outliers, and there are not enough distinct different forecasts for the mode to be meaningful.