under or over-absorbed overhead

under or over-absorbed overhead　少吸收或多吸收的制造费用　

Usually overheads are apportioned or allotted to cost units on an estimated basis.But it is quite natural that the overhead so estimated may be different from the amount of overhead actually incurred.Hence the question of under or over absorption of overhead arises when there is a difference between the amount of overhead absorbed and the amount of overhead incurred.