This adjective means 'unseen' or 'hidden,' often referring to things below the earth or concealed from view. In Hebrews 4:13, it appears in the striking declaration that 'no creature is hidden from God's sight'—nothing is invisible (ἀφανής) before the One to whom we must give account. The term underscores divine omniscience: what remains unseen to human eyes is fully exposed to God. Classical usage includes references to the underworld, disappeared persons, and secret actions. The writer to the Hebrews deploys it to demolish any illusion of privacy before the all-seeing Creator.