Dasa is a Sanskrit word found in ancient Indian texts such as the Rigveda, Pali canon, and the Arthashastra. The term may mean "slave", "enemy" or "servant," but Dasa or Das can also have the following connotations: "slave of god", "devotee," "votary" or "one who has surrendered to God." Dasa may be a suffix of a given name to indicate a "slave" of a revered person or a particular deity.

Dasa, in some contexts, is also related to dasyu and asura, which have been translated by some scholars as "demon", "harmful supernatural forces," "slave," "servant," or "barbarian," depending on the context in which the word is used.

Dāsa first appears in Vedic texts from the second millennium BCE. There is no consensus on its origins.

Karl Heinrich Tzschucke in 1806, in his translations of the Roman geographer Pomponius Mela, noted etymological and phonological parallels between dasa and the ethnonyms of the Dahae – Persian داها; Sanskrit Dasa; Latin Dahae; Greek Δάοι Daoi, Δάαι, Δᾶαι Daai and Δάσαι Dasai – a people who lived on the south-eastern shores of the Caspian Sea in ancient times (and from whom modern Dehestan/Dehistan takes its name).

Monier Monier-Williams in 1899, stated that the meaning of dasa varies contextually and means "mysterious forces", "savages", "barbarians" or "demons" in the earliest layer of Vedic literature – in other contexts, is a self-effacing way to refer oneself as "worshipper" or "devotee aiming to honor a deity", or a "servant of god". In later Indian literature, according to Monier-Williams, usage of dasa is used to refer to "a knowing man, or a knower of the universal spirit". In the latter sense, dāsa is masculine, while the feminine equivalent is dāsi. Some early 20th century translators, such as P. T. Srinivasa Iyengar (1912), translate dasa as "slave".

Kangle in 1960, and others suggest that, depending on the context, dasa may be translated as "enemy", "servant" or "religious devotee". More recent scholarly interpretations of the Sanskrit words dasa or dasyu suggest that these words used throughout the Vedas represents "disorder, chaos and dark side of human nature", and the verses that use the word dasa mostly contrast it with the concepts of "order, purity, goodness and light." In some contexts, the word dasa may refer to enemies, in other contexts it may refer to those who had not adopted the Vedic beliefs, and yet other contexts it may refer to mythical enemies in the battle between good and evil.

In Pali texts, the term dasa is mentioned to denote a slave. Dasa in Buddhist texts can mean "servant". In Pali language, it is used as suffix in Buddhist texts, where Amaya-dasa was translated by Davids and Stede in 1925, as a "slave by birth", Kila-dasa translated as a "bought slave", and Amata-dasa as "one who sees Amata (Sanskrit: Amrita, nectar of immortality) or Nibbana (Sanskrit: Nirvana)".

According to Dr. Bhimrao Ambedkar, regarding the Dasas, the question is whether there is any connection between the Azhi-Dahaka of the Zend Avesta. The name Azhi-Dahaka is a compound name which consists of two parts. Azhi means serpent or dragon and Dahaka comes from the root "Dah" meaning "to sting, to do harm"