Sat (Sanskrit: सत्) is a Sanskrit word meaning "the true essence" and "which is unchangeable" of an entity, species or existence. Sat is a common prefix in ancient Indian literature and variously implies that which is good, true, virtuous, being, happening, real, existing, enduring, lasting, essential. In ancient texts, fusion words based on Sat, refer to "Universal Spirit, Universal Principle, Being, Soul of the World, Brahman".
Sat is the root of many Sanskrit words and concepts such as sattva "pure, truthful" and satya "truth". As a prefix, in some context it means true and genuine; for example, sat-sastra means true doctrine, sat-van means one devoted to the true.
Sat may also refer to Citsvaru'pa, the Supreme consciousness, or Parama Purusha, the Supreme Being. "Sat" is one of the three characteristics of Brahman, as described in sat-chit-ananda.