A-priori: knowledge, understanding or justification derived independently of sensory experience.

Derived independently of sense experience e.g., 2+2=4. Truth by definition and tautological deduction is the mathematical model, but presuppositions are often falsely assumed a-priori.

Source: What is Good? What is Bad? The Value of All Values across Time, Place and Theories’ by John McMurtry, Philosophy and World Problems, Volume I-III, UNESCO in partnership with Encyclopedia of Life Support Systems: Oxford, 2004-11.