Fill to a lower level than needed.
Insufficiently complete a container or space.
Provide inadequate material for support structures.
Leave gaps in filling processes or applications.
Fail to meet required volume specifications.
Insufficient material in a manufacturing process.
Inadequate filling of voids or gaps.
A specific instance of underfilling an item.
Deficiency in content within containers or spaces.
The act of intentionally leaving space unfilled.
Underleveling soil beneath structures for support stability.