bedrock

In a geological sense, this term refers to the hard, unbroken rock that lies beneath the soil and sediment. It implies a state of absolute stability and permanence, serving as the physical foundation for everything above it. When used figuratively, it describes the indispensable core values or primary facts that support a system, belief, or relationship. It carries a strong connotation of reliability and strength, suggesting that if this foundation were removed, the entire structure would collapse.