Definition - What does Suddha mean?
Suddha is a Sanskrit word that means “purity.” It is an important concept in certain schools of Buddhism and is also found in Hindu and yogic philosophy. Another Sanskrit word, sattva, is sometimes used as a synonym for suddha, although sattva is also defined as “goodness.” The combined term of suddha-sattva is a concept meaning “state of pure goodness,” or the state of Self-realization.
Ways of achieving suddha vary by tradition, but may include elements of yoga practice including meditation, pranayama and asana practice, as well as study of scriptures and following a strict suddha diet to purify the body.
Yogapedia explains Suddha
Among other terms that use the word, suddha, in Indian philosophy and religion are suddha vichara, which refers to pure thoughts; suddha vidya, which means “pure wisdom”; and suddha ahara, which refers to pure food or that which best nourishes the body. In addition, suddha manas, or "pure mind," is a necessary state for effective meditation. Without suddha manas, the yogi cannot achieve higher states of consciousness. The asuddha manas, or "impure mind," prevents Self-realization.
In some Buddhist traditions, suddha is the concept of moral purification. The belief is that nirvana (the state of bliss and freedom from the cycle of rebirth) can be achieved only if the Buddhist purifies him/herself of the kleshas (negative mental states) and all moral and character defects. In Mahayana Buddhist sutras, though, both suddha and asuddha ("impurity") are described as illusion, yet the Buddhist still must detach in order to reach the state of nirvana.