Deva (; Sanskrit: , ) means "shiny", "exalted", "heavenly being", "divine being", "anything of excellence", and is also one of the Sanskrit terms used to indicate a deity in Hinduism. Deva is a masculine term; the feminine equivalent is Devi. In the earliest Vedic literature, all supernatural beings are called Devas and Asuras. The concepts and legends evolved in ancient Indian literature, and by the late Vedic period, benevolent supernatural beings are referred to as Deva-Asuras. In post-Vedic Hindu texts, such as the Puranas and the Itihasas of Hinduism, the Devas represent the good, and the Asuras the bad. In some medieval works of Indian literature, Devas are also referred to as Suras and contrasted with their equally powerful but malevolent half-brothers, referred to as the Asuras. Devas, along with Asuras, Yakshas (nature spirits), and Rakshasas (ghoulish ogres/demons), are part of Indian mythology, and Devas feature in many cosmological theories in Hinduism. Etymology Deva is a Sanskrit word found in Vedic literature of 2nd millennium BCE. Monier-Williams translates it as "heavenly, divine, terrestrial things of high excellence, exalted, shining ones". The concept also is used to refer to deity. The Sanskrit deva- derives from Indo-Iranian *daiv- which in turn descends from the Proto-Indo-European word, *deiwo-, originally an adjective meaning "celestial" or "shining", which is a (not synchronic Sanskrit) vrddhi derivative from *diw, zero-grade of the root *dyew- meaning "to shine", especially as the day-lit sky. The feminine form of *deiwos is *deiwih2, which descends into Indic languages as devi, in that context meaning "female deity". Also deriving from *deiwos, and thus cognates of deva, are "Zeys/Ζεύς" - "Dias/Δίας", the Greek father of the gods, Lithuanian Dievas (Latvian Dievs, Prussian Deiwas), Germanic Tiwaz (seen in English "Tuesday") and the related Old Norse Tivar (gods), and Latin Deus "god" and divus "divine", from which the English words "divine" and "deity" are derived. It is related to *Dyeus which while from the same root, may originally have referred to the "heavenly shining father", and hence to "Father Sky", the chief God of the Indo-European pantheon, continued in Sanskrit Dyaus. The abode of the Devas is Dyuloka. According to Douglas Harper, the etymological roots of Deva mean "a shining one," from *div- "to shine," and it is cognate with Greek dios "divine" and Zeus, and Latin deus "god" (Old Latin deivos). The word "Deva" shares similarities with Persian Daeva. Deva is masculine; the related