Sadhu in the context of "Sādhanā"

Sannyasa (Sanskrit: संन्यास, romanized: saṃnyāsa), sometimes spelled sanyasa, is the fourth stage within the Hindu system of four life stages known as ashramas, the first three being brahmacharya (celibate student), grihastha (householder) and vanaprastha (forest dweller, retired). Sannyasa is traditionally conceptualized for men or women in the last years of their life, but young brahmacharis have the choice to skip the householder and retirement stages, renounce worldly and materialistic pursuits and dedicate their lives to spiritual pursuits.

Sannyasa, a form of asceticism marked by renunciation of material desires and prejudices, is characterized by a state of uninterest in and detachment from material life, with the purpose of spending one's life in peaceful, spiritual pursuits. An individual in Sanyasa is known as a sannyasi (male) or sannyasini (female) in Hinduism. Sannyasa shares similarities with the Sadhu and Sadhvi traditions of Jain monasticism, and the sannyasi and sannyasini share similarity with the bhikkhus and bhikkhunis of Buddhism.

Siddha (Sanskrit: सिद्ध siddha; "perfected one") 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 perfection of the intellect as well as liberation 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.

A Digambara monk or Digambara Sādhu (also muni, sādhu) is a Sādhu in the Digambar tradition of Jainism, and as such an occupant of the highest limb of the four-fold sangha. Digambar Sādhus have 28 primary attributes which includes observance of the five supreme vows of ahimsa (non-injury), truth, non-thieving, celibacy and non-possession. A Digambar Sādhu is allowed to keep only a feather whisk, a water gourd and scripture with him.

In Jainism, those śrāvakas (householders) who wish to attain moksha (liberation) renounce all possessions and become an ascetic. According to the Jain text, Dravyasamgraha:

Akhara or Akhada (Hindi: अखाड़ा, romanised: Akhāṛā) is an Indian word for a place of practice with facilities for boarding, lodging and training, both in the context of Indian martial artists or a sampradaya monastery for religious renunciates in Guru–shishya tradition. For example, in the context of the Dashanami Sampradaya sect, the word denotes both martial arts and religious monastic aspects of the trident-wielding martial regiment of the renouncing sadhus.

Tapovana (Sanskrit) comes from the two root words tapas, meaning 'penance' and by extension 'religious mortification' and 'austerity', and more generally 'spiritual practice', and vana, meaning 'forest' or 'thicket'. Tapovana then translates as 'forest of austerities or spiritual practice'. Though pronounced the same in Hindi, tapovana should not be confused with tapovan (from tapovat), which means a person engaged in austerity.

Traditionally in India, any place where someone has engaged in serious spiritual retreat may become known as a tapovana, even if there is no forest. As well as particular caves and other hermitages where sages and sadhus have dwelt, there are some places, such as the western bank of the northern Ganges river around Rishikesh, that have been so used by hermits that the whole area has become known as a tapovana.

Udasis (Gurmukhi: ਉਦਾਸੀ ਸੰਪਰਦਾ; udāsī saparadā) (Devanagari: उदासी संप्रदाय), also spelt as Udasins, also known as Nanak Putras (meaning "sons of Nanak"), are a religious sect of ascetic sadhus centred in northern India who follow a tradition known as Udasipanth. Becoming custodians of Sikh shrines in the 18th century, they were notable interpreters and spreaders of the Sikh philosophy during that time. However, their religious practices border on a syncretism of Sikhism and Hinduism, and they did not conform to the Khalsa standards as ordained by Guru Gobind Singh. When the Lahore Singh Sabha reformers, dominated by Tat Khalsa Sikhs, would hold them responsible for indulging in ritual practices antithetical to Sikhism, as well as personal vices and corruption, the Udasi mahants were expelled from the Sikh shrines.

Sādhanā (Sanskrit: साधना; Tibetan: སྒྲུབ་ཐབས་, THL: druptap; Chinese: 修行; pinyin: xiūxíng) is an ego-transcending spiritual practice in Indian religions. It includes a variety of disciplines in Hindu, Buddhist and Jain traditions that are followed in order to achieve various spiritual or ritual objectives.

Sadhana is done for attaining detachment from worldly things, which can be a goal of a sadhu. Karma yoga, bhakti yoga and jnana yoga can also be described as sadhana; constant efforts to achieve maximum level of perfection in all streams of day-to-day life can be described as Sadhana.