Fundamental Principles on Which a Thing Is Based
This page is the CodyCross answer for the clue below from Health and Fitness, Group 2138, Puzzle 1 (Weighted Vests).
Question is: Fundamental Principles on Which a Thing Is Based
and the answer is: BEDROCK
Word Meaning:
BEDROCK — (countable, uncountable, geology, mining, engineering, construction) The solid rock found at some depth below the ground surface.
Definitions from Wiktionary.