An adjective that refers to the result of an Integral, or in some cases even a discrete sum. Used a lot in statistical methods. If one integrates a function over a variable, the result is no longer a function of that variable. This is useful for reducing the complexity of a system of information for purposes of interpretation.
If you do not understand, imagine an actuary (let's call him Bob) at a HMO. Bob is trying to figure out what portion of people who smoke get lung cancer within ten years of starting smoking, based on age started. But his data are grouped by region, which he (for the moment) doesn't care about. So, for each age group, Bob adds up the numbers from each region, and considers the totals across all regions only. This is essentially the integral over regions of his data. He may wish to consider regional effects later (he will if he is a good actuary), but for now he has the data given independent of region, simplifying his task tremendously.