Sunyata in Buddhist philosophy means nothingness; the voidness that constitutes ultimate reality.
In the English language there is no word which can be appropriately equivalent, to Sunyata.
It means emptiness; but not negative, very positive emptiness. It also means nothingness, but it does not mean simply nothingness; it means “no-thing-ness”. It is the void of everything.
The void itself is there, with utter presence, so it is not just void. It is like the sky which is empty, which is pure space, in to which everything comes in and goes, yet it remains.
Sunyata is pure presence. You cannot touch it although you live in it. You cannot see it although you can never be without it.
You exist in it; just as the fish exists in the ocean, you exist in space, in Sunyata.
Sunyata means that everything arises out of no-thing.
Reality means the world of things, and truth means the world of no-thing = nothing -- Sunya.
In Hindi the word “Sunya” derived from the Sanskrit word Sunyata also means ‘void, vacuum, emptiness, boundless’
All things arise out of nothing and dissolve back into nothing.
In the Upanishads there is a story:
Svetaketu had just returned come from his Guru’s house, back to his parents. He had gained much knowledge from his Guru.
His father, Uddalaka, a great philosopher, looked at him and said, “Svetaketu, go outside in the garden and bring a fruit from any tree.”
He goes out, brings a fruit, and the father says, "Break it. What do you see in it?"
Svetaketu replied that there were many seeds in it.
The father then says, "Take one seed and break it. What do you see in it?"
Svetaketu replied, "Nothing"
The father then explains,
"Everything arises out of this nothing.
This big tree in the garden is so huge that it can provide shelter and rest for dozens of people underneath it ; such a magnificent tree has arisen only out of just a tiny seed.
Yet when you broke the seed, there is nothing in there.
This is the mystery of life - Everything arises out of nothing.
One day this same tree will disappear and you will not know where it went ; you simply cannot find it anywhere."
So does Man: we arise out of nothing, and we are nothing, and we disappear into nothing.