Avijjā: Ignorance, nescience, the blindness of not knowing, is synonymous with confusion moha (see mūla), is the primary & deepest root of all evil and suffering in the world, veiling man's mental eyes and preventing him from seeing the true nature of things. It is the confusion that fools beings by making life appear to them as permanent, happy, substantial and beautiful and preventing them from seeing that everything in reality is impermanent, liable to suffering, void of 'I' and 'mine', and basically impure see: vipallāsa. Ignorance is defined as not knowing The Four Noble Truths, namely, suffering, its origin, its cessation, and the way to its ceasing see: S. XII, 4.
Maha Thera Nyanatiloka. Manual of Buddhist Terms and Doctrines, Buddhist Publication Society, first edition 1952.