Tetralemma means A, ~A, both neither.
Aristotle’s Metaphysics was written to refute the very idea of it.
It is the way that Nagarjuna and perhaps the Buddha as well-defined emptiness.
It exhaust all logical possibilities and points to and impossible necessary possibility that we call emptiness that is non-cardinal, i.e. Not One! Not Two! Not Three! Not Many!.
Emptiness is seen as the ultimate nature of the mind and though that everything else that we know through the mind including the void of nature that is like empty space.
Emptiness is non conceptualizable and non-experiential because it falls outside the realm of logical possibilities.
Emptiness is not the Tetralemma, but is what is indicated by the Tetralemma as Other than it.
It turns out that this is a way of defining the Absolute. The absolute can be thought of as what falls outside the Tetralemma.
One way to interpret that is to say that Buddhism does not hold anything absolute, and is absolute about that stance against absolutes.
Another way to think about it is that everything is basically in a state of flux in which even change continually changes but not in a way that is itself continuous, rather in a way in which everything is discontinuous, i.e. is aggregates in flux such that the flux is also in flux. This type of change of change leaves no reference point we can rely on to even measure the change. And in that sense it is an absolute that is against all permanent, and unchanging absolutes. It is an absolute that destroys all other absolutes.