Apologies for not using plain English, part of my intention is to help intermediate & advanced learners of Pali so this post may not make full sense to those who are only beginning to learn Pali / Sanskrit.
The word avidyā, like the word anātman is called a nañ-tatpuruṣa (a determinative compound formed with the word ‘na’ - i.e. here the words in the compound are na & vidyā).
The ancient thesaurus Amarakoṣa equates avidyā to ajñāna & aham-mati . The Pāli thesaurus Abhidhānappadīpikā (which is based on the Amarakoṣa) does not directly define avijjā but equates vijjā (vidyā) to ñāṇa (jñāna)
A nañ-tatpuruṣa compound can have the following 6 possible meanings (and must be construed using all these possible senses to get a wholistic mental-picture of the word’s semantic-range):
- sādṛśye yathā — abrāhmaṇaḥ brāhmaṇasadṛśa ityarthaḥ
- abhāve yathā — abhojanaṁ bhojanābhāvaḥ
- anyatve yathā — aghaṭaḥ ghaṭabhinna ityarthaḥ
- alpatve yathā — anudarī kanyā alpodarī ityarthaḥ
- aprāśastye yathā — adhanaṁ apraśastadhanam ityarthaḥ
- virodhe yathā — adharmaḥ dharmavirodhī ityarthaḥ