Definition: Apertius is a term in classical Greek philosophy that refers to "clear." It implies clarity or simplicity, often associated with spiritual or philosophical teachings, especially those dealing with the nature of God or religion itself. The noun form of apertius means "clear," and this adjective emphasizes its quality and purity. Definition: Apertius signifies clarity, truthfulness, or a state of being pure, unblemished, and without confusion. Aperture in architecture refers to a small opening through which light enters or exits an aperture (a door, window, etc.)