backfill

[bak-fil]
verb (used with object)
  1. to refill (an excavation).

Origin of backfill

First recorded in 1950–55; back2 + fill
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

British Dictionary definitions for backfill

backfill

verb
  1. (tr) to refill an excavated trench, esp (in archaeology) at the end of an investigation
noun
  1. the soil used to do this
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Word Origin and History for backfill
n.

1901 (as backfilling), from back (adj.) + fill (n.). The verb was in use by 1930.

Online Etymology Dictionary, © 2010 Douglas Harper