Thoroughly, completely, as in This new job suits him down to the ground. [Colloquial; second half of 1800s]
The American Heritage® Idioms Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.
How to use down to the ground in a sentence
How are we to get the down-to-the-ground work of the land done without the aid of such?Criminal Types | V. M. Masten