Siddha
Siddha is a term that is used widely in Indian religions and culture. It means "one who is accomplished". It refers to perfected masters who have achieved a high degree of physical as well as spiritual perfection or enlightenment. In Jainism, the term is used to refer to the liberated souls. Siddha may also refer to one who has attained a siddhi, paranormal capabilities.
Siddhas may broadly refer to siddhars, naths, ascetics, sadhus, or yogis because they all practice sādhanā.
The Svetasvatara presupposes a Siddha body.
Jainism
In Jainism, the term siddha is used to refer the liberated souls who have destroyed all karmas and have obtained moksha. They are free from the transmigratory cycle of birth and death and are above Arihantas. Siddhas do not have a body; they are soul in its purest form. They reside in the Siddhashila, which is situated at the top of the Universe. They are formless and have no passions and therefore are free from all temptations. They do not have any karmas and they do not collect any new karmas.According to Jains, Siddhas have eight specific characteristics or qualities. Ancient Tamil Jain Classic 'Choodamani Nigandu' describes the eight characteristics in a poem, which is given below.
"கடையிலா ஞானத்தோடு காட்சி வீரியமே இன்ப
மிடையுறு நாமமின்மை விதித்த கோத்திரங்களின்மை
அடைவிலா ஆயுஇன்மை அந்தராயங்கள் இன்மை
உடையவன் யாவன் மற்று இவ்வுலகினுக்கு இறைவனாமே"
"The soul that has infinite knowledge, infinite vision or wisdom,
infinite power, infinite bliss,
without name, without association to any caste,
infinite life span and without any change is God."
The following table summarizes the eight supreme qualities of a liberated soul.
| Quality | Meaning | Manifestation |
| Kśāyika samyaktva | infinite faith or belief in the tattvas or essential principles of reality | manifested on the destruction of the faith-deluding karma |
| Kevala Jnāna | infinite knowledge | on the destruction of the knowledge-obscuring karma. |
| Kevaladarśana | infinite perception | on the destruction of the perception-obscuring karma |
| Anantavīrya | infinite power | on the destruction of the obstructive karma |
| Sūksmatva | fineness | manifested on the destruction of the life- determining karma |
| Avagāhan | inter-penetrability | manifested on the destruction of the name-determining karma |
| Agurulaghutva | literally, neither heavy nor light | manifested on the destruction of the status-determining karma |
| Avyābādha | undisturbed, infinite bliss | manifested on the destruction of the feeling-producing karma |
Because of the quality of Sūksmatva, the liberated soul is beyond sense-perception and its knowledge of the substances is direct, without the use of the senses and the mind. The quality of avagāhan means that the liberated soul does not hinder the existence of other such souls in the same space.
A soul after attaining Siddhahood goes to the top of the loka and stays there till infinity. Siddhas are formless and dwell in Siddhashila with the above-mentioned eight qualities.
Hinduism
In Hinduism, the first usage of the term Siddha occurs in the Maitreya Upanishad in chapter Adhya III where the writer of the section declares "I am Siddha."Siddha or siddhar (Tamil tradition)
In Tamil Nadu, South India, a siddha refers to a being who has achieved a high degree of physical as well as spiritual perfection or enlightenment. The ultimate demonstration of this is that siddhas allegedly attained physical immortality. Thus siddha, like siddhar, refers to a person who has realised the goal of a type of sadhana and become a perfected being. In Tamil Nadu, South India, where the siddha tradition is still practiced, special individuals are recognized as and called siddhas who are on the path to that assumed perfection after they have taken special secret rasayanas to perfect their bodies, in order to be able to sustain prolonged meditation along with a form of pranayama which considerably reduces the number of breaths they take. Siddha were said to have special powers including flight. These eight powers are collectively known as attamasiddhigal. In Hindu cosmology, Siddhaloka is a subtle world where perfected beings take birth. They are endowed with the eight primary siddhis at birth.The 18 siddhars are listed below.
Kashmir Shaivism
In the Hindu philosophy, siddha refers to a Siddha Guru who can by way of Shaktipat initiate disciples into Yoga. A Siddha, in Tamil Siddhar or Chitthar, means "one who is accomplished" and refers to perfected masters who, according to Hindu belief, have transcended the ahamkara, have subdued their minds to be subservient to their Awareness, and have transformed their bodies into a different kind of body dominated by sattva. This is usually accomplished only by persistent meditation.Siddhashrama
In Hindu theology, Siddhashrama is a secret land deep in the Himalayas, where great yogis, sadhus and sages who are siddhas live. The concept is similar to Tibetan mystical land of Shambhala.Siddhashrama is referred in many Indian epics and Puranas including Ramayana and Mahabharata. In Valmiki's Ramayana it is said that Viswamitra had his hermitage in Siddhashrama, the erstwhile hermitage of Vishnu, when he appeared as the Vamana avatar. He takes Rama and Lakshmana to Siddhashrama to exterminate the rakshasas who are disturbing his religious sacrifices.