To refill an excavated area with the material that was removed. After installing the pipes, the workers backfilled the trench to restore the ground level.
To provide a replacement for a position or role that has been vacated. The company decided to backfill the manager's position after she left for another job.
To add or load historical or missing data into a system, database, or dataset. They had to backfill the database with records from the past five years.