Bedrock and Boulder

Bedrock noun - An immaterial thing upon which something else rests.

Boulder and bedrock are semantically related in nature topic. In some cases you can use "Boulder" instead a noun "Bedrock".

Boulder noun - A large smooth mass of rock detached from its place of origin.

Bedrock and boulder are semantically related in nature topic. You can use "Bedrock" instead a noun "Boulder", if it concerns topics such as stone.