adj. & adv.
adj. 1 (of reasoning) deductive; proceeding from causes to effects (opp. A POSTERIORI). 2 (of concepts, knowledge, etc.) logically independent of experience; not derived from experience (opp. EMPIRICAL). 3 not submitted to critical investigation (an a priori conjecture).
adv. 1 in an a priori manner. 2 as far as one knows; presumptively. apriorism n.
[ L, = from what is before ]