What is the meaning of term "ignorance" in Upanishads and Vedas?

Question

The word ignorance is related to knowledge of Brahman or what.

Answer 1

Ignorance or avidya is an Advaita Vedanta term. It hides Brahman and makes it appear as the universe. It is the same as maya.

Ignorance (Avidya)

Advaita Vedanta says that ignorance of Brahman has created this world. Ignorance, which is the opposite of knowledge (jnana-virodhi), is not something negative. It has a positive character (bhavarupa).

It has two powers: (1) the veiling power (avarana-shakti) and (2) the power of projection (vikshepa-shakti). Ignorance has the power to cover or veil the Reality, which is Brahman, and also the power to project this world on the veiled or covered Reality.

The world is the product of mula-avidya. The individual ego, which is part of this world, is also the product of mula-avidya. Consciousness associated with this ego is called the Atman or the Jivatman. Between the Jivatman and Brahman (Paramatman) there is a thin veil of ignorance. It is like a cloud that does not all an individual to see the sun. In this analogy the Brahman is the sun and the patch of cloud is the ignorance of the individual. When this individual’s ignorance is dispelled by the knowledge of Brahman, he or she will have the experience of Brahman.

The Journey from Many to One essentials of Advaita Vedanta by Swami Bhaskarananda

Maya

From the point of view of Advaita Vedanta, maya and avidya are the same. Just as avidya or ignorance has the powers, as it were, to hide Brahman and project something else, such as the world, on it, so also maya, as it were, can cover up Brahman and project the world onto it.

Maya cannot really cover the Reality that is Brahman. A patch of cloud can never cover the sun. It only covers the eyes of those who are looking at the sun. In the same way maya covers our knowing ability and thus obstructs our knowledge of Brahman.

In any act of knowing, the ‘knower’ and the object known’ have to be separate from each other. They cannot be the same. In order for us to know maya, it has to be separate from us. Individuals like us are the products of maya and we are all posited within the domain of maya. Maya and we individuals are not separate from each other, just as chocolate and a bear-shaped chocolate candy are not different from each other.

As we are identical with maya, we cannot know maya. For this reason, maya is not only unknowable; it is inexplicable as well (anirvachaniya).

The Journey from Many to One essentials of Advaita Vedanta by Swami Bhaskarananda

Answer 2

Well as per the Brahma Bindu Upanishad due to Maya it's being compared to darkness of not knowing the Truth i.e the Brahman:

Verse

शब्दमायावृतो यावत्तावत्तिष्ठति पुष्करे। भिन्ने तमसि चैकत्वमेकमेवानुपश्यति ॥

Transliteration

śabdamāyāvṛto yāvattāvattiṣṭhati puṣkare। bhinne tamasi caikatvamekamevānupaśyati ॥

Hindi Meaning

जब तक नाम-रूपात्मक अस्तित्व रखने वाली माया के द्वारा (यह) जीवात्मा आवृत रहता है, तब तक बँधे हुए की भाँति हृदय-कमल में स्थित रहता है, जब अज्ञान रूपी अन्धकार का विनाश हो जाता है, तब ज्ञान रूपी प्रकाश में विद्वान् पुरुष जीवात्मा एवं परमात्मा के एकत्व का दर्शन प्राप्त कर लेता है ॥

English:

As long as (it) is encompassed by the Maya possessing the name-morphological existence, it remains in the heart-lotus like the bound, when the darkness of ignorance is destroyed, then the learned man in the light of knowledge One attains the vision of the oneness of the soul and the divine.