Avijjāsutta
Sāvatthinidānaṁ. Atha kho aññataro bhikkhu yena bhagavā tenupasaṅkami …pe… ekamantaṁ nisinno kho so bhikkhu bhagavantaṁ etadavoca: “‘avijjā, avijjā’ti, bhante, vuccati. Katamā nu kho, bhante, avijjā; kittāvatā ca avijjāgato hotī”ti? “Idha, bhikkhu, assutavā puthujjano rūpaṁ nappajānāti, rūpasamudayaṁ nappajānāti, rūpanirodhaṁ nappajānāti, rūpanirodhagāminiṁ paṭipadaṁ nappajānāti; vedanaṁ nappajānāti … saññaṁ … saṅkhāre nappajānāti …pe… viññāṇanirodhagāminiṁ paṭipadaṁ nappajānāti. Ayaṁ vuccati, bhikkhu, avijjā; ettāvatā ca avijjāgato hotī”ti.
Ignorance
At Sāvatthī. Then a mendicant went up to the Buddha and said to him: “Sir, they speak of this thing called ‘ignorance’. What is ignorance? And how is an ignoramus defined?” “Mendicant, it’s when an unlearned ordinary person doesn’t understand form, its origin, its cessation, and the practice that leads to its cessation. They don’t understand feeling … perception … choices … consciousness, its origin, its cessation, and the practice that leads to its cessation. This is called ignorance. And this is how an ignoramus is defined.”