average cost
Average cost is the amount assigned to each unit when inventory or investments are valued using the total recorded cost divided by the total number of units owned. As quantities are acquired or disposed of, the unit figure is recalculated from the updated totals, so all units are generally carried at the same blended value rather than at separate transaction prices.
Source: European Central Bank (ECB) (source). This glossary entry is an independently worded adaptation of the cited information.