Akasa or “Akasha” – the root is kash – “to shine”, the A-prefix here denotes near, back, or inwards-turning, hence “inner radiance”. General interpretations of Akasa include: space, sky, radiance. Akasa is often translated as “ether”.
Akasa is limitless and all-pervasive. It gives space and time their continuity.
Akasa is often used to denote the transcendent self – which is described as shining brighter than one thousand suns. In the Brihad-Aranyaka-Upanishad akasa is said to reside in the heart.