from The American Heritage® Dictionary of the English Language, 4th Edition
- n. Material used to refill an excavated area.
- transitive v. To refill (an excavated area) with such material.
from Wiktionary, Creative Commons Attribution/Share-Alike License
- v. To refill a hole with the material dug out of it.
- v. To refill an excavation unit to restore the former ground surface and or to preserve the unit and make it recognizable as having been excavated.
- v. To provide reserve support.
- v. To replenish or restock due to attrition or loss.
- n. The material that has been used to refill an excavation.
- n. Reserve support personnel.
- n. That which backfills; a replacement.
from The Century Dictionary and Cyclopedia
- In engineering, to fill (a depression) with material taken from a cutting.
From back + fill. (Wiktionary)