The Greek term denotes something solid and immovable—a foundation, framework, or firm support. Classical usage speaks of the skeleton as the body's framework and uses the term for the firmament or vault of heaven. Paul employs this architectural and structural imagery to describe the Colossian church's faith as having solidity and stability despite his physical absence. The term suggests not rigidity but reliable structural integrity. Peter similarly warns against falling from one's 'own steadfastness' through deception, emphasizing the need for maintained stability.