bedrock

The solid layer of rock underneath soil and loose stones.

• The builders reached bedrock.
• We drilled through the soil into bedrock.
• Glaciers had scraped away the soil, exposing the bedrock.

Common phrases: solid bedrock, exposed bedrock, reach bedrock, drill into bedrock

The main idea, belief, or support on which something depends.

• Trust is the bedrock of our relationship.
• These values formed the bedrock of her teaching.
• Small businesses remain the bedrock of the local economy.

How to use it: the bedrock of something (Trust is the bedrock of a good friendship.)

Similar words: foundation, basis, cornerstone

Common phrases: bedrock of something, form the bedrock, bedrock principle