Asura has two renderings: an ancient and esoteric one, and a later and exoteric one. The oldest meaning of Asura as used in the Rig-Veda is ‘a divine spirit,’ derived from asu — breath. The word Asura was also applied to those classes of beings now spoken of as Kumaras, Agnishwattas, and Manasaputras, those fallen angels, the fathers of our higher natures, who thus imbodied themselves in order to attain greater wisdom and a fuller awareness of their divine natures. Later when the keys to the mystery-teachings were lost and theological dogma arose among the Brahmanical sects, the Asuras, within or without man, who opposed the empty ritualism and sacrificial ceremonial of the time, were then called ‘elemental-gods’ or ‘demons’ by these followers of false gods and of exoteric form, and the derivation of the word was changed to a — not, and sura — god; and hence Asura soon became synonymous with ‘demon,’ and in most of the later literature of India Asuras are ‘demons,’ those who oppose the works of the gods. H.P. Blavatsky, The Voice of Silence
Originally the word stood for the supreme spirit (being so used in the Rig-Veda), and equivalent to the Zoroastrian Ahura Mazda; then it became applied to deities, such as Indra, Agni and Varuna; later still it denoted a class of elemental beings evil in nature, and consequently Asuras are termed demons. The Taittiriya-Brahmana represents the Asuras as being created from the breath of Brahma-Prajapati likewise the Laws of Manu, but the Puranas indicate that they sprang from his thigh. “Esoterically, the Asuras, transformed subsequently into evil Spirits and lower gods, who are eternally at war with the great deities — are the gods of the Secret Wisdom. . . . They are the sons of the primeval Creative Breath at the beginning of every new Mahakalpa, or Manvantara; . . . Evidently they have been degraded in Space and Time into opposing powers or demons by the ceremonialists,” (Secret Doctrine, II, pp. 500-1). (The following word is derived from the verbal root:) as, to breathe. Bhagavad-Gita, W. Q. Judge, p. 65) Gods and Heroes of the Bhagavad Gita, Geoffrey A. Barborka