Q: Do you have the perfect definition of Consciousness as per Advaita Vedanta?
A: Traditional Advaita prefers to use ‘Brahman’ as referring to the absolute reality, although the aitareya upaniShad says ‘praj~nAnaM brahma’, which is translated as ‘Consciousness is Brahman’. Probably the most famous ‘definition’ (as far as that is possible) is the one in the Taittiriya Upanishad (2.1.1): satyam j~nAnam anantam brahma – Brahman is real/truth/existence – knowledge/consciousness – limitless.
And in 3.1.2, the same Upanishad says that one should strive to know that from which all these beings are born, that in which they live and exist, and that to which they return – that is Brahman.
Brahman is the sRRiShTi sthiti laya kAraNa – the cause of the creation, maintenance and destruction of everything.
And so on! There are lots of ‘pointers’ but no definition as such, as explained in the answers above.
Q: Maybe I’m asking about consciousness with a lower case ‘c’ – I just want to know how you would define that word.
A: Nothing special here. The Sanskrit word is ‘chit’. Swami Dayananda’s definition is ‘limitless self-effulgent awareness; the self-revealing’. The book ‘A-U-M’ tells you all about the ‘states of consciousness’ and that their ‘substratum’ is turIya. See the article I wrote about ‘states’ of consciousness (https://www.advaita-vision.org/states-of-consciousness-2-3-4-and-1-2/).