Avadhūta (IAST avadhūta) is a Sanskrit term from the root 'to shake' (see V. S. Apte and Monier-Williams) that, among its many uses, in some Indian religions indicates a type of mystic or saint who is beyond egoic-consciousness, duality and common worldly concerns and acts without consideration for standard social etiquette. Avadhuta is a Jivanmukta who gives his insight to others and teach them about his realisation of the true nature of the ultimate reality (Brahman) and self (Atman) and takes the role of a guru to show the path of moksha to others. Some Avadhuta also achieve the title of Paramahamsa.
Similar figures (colloquially called 'mad/crazy monks') are also known in Buddhist traditions, such as the medieval Zen monk Ikkyū, and the 20th century Tibetan tulku Chögyam Trungpa Rinpoche. In Tibetan Buddhism the equivalent type is called a nyönpa (Wylie: smyon pa).
Feuerstein (1991: p. 105) frames how the term avadhūta came to be associated with the mad or eccentric holiness or 'crazy wisdom' of some antinomian paramahamsa who were often 'skyclad' or 'naked' (Sanskrit: digambara):
The appellation "avadhūta," more than any other, came to be associated with the apparently crazy modes of behaviour of some paramahamsas, who dramatize the reversal of social norms, a behaviour characteristic of their spontaneous lifestyle. Their frequent nakedness is perhaps the most symbolic expression of this reversal."
ཀུ་སུ་ལུ་པ ku-su-lu-pa is a word of Tantrik mysticism, its proper Tibetan equivalent being གཅོད་པ, the art of exorcism. The mystic Tantrik rites of the Avadhauts, called Avadhūtipa in Tibet, exist in India.
The rites of Chöd differ between lineages but essentially there is an offering of their body as food, a blessing to demons and other entities to whom this kind of offering may be of benefit, the ganachakra. This leitmotif and sādhanā is common to another denizen of the charnel ground, Dattatreya the avadhūta, to whom has been attributed the esteemed nondual medieval song, the Avadhuta Gita. Dattatreya was a founding adiguru of the Aghori according to Barrett (2008: p. 33):
Lord Dattatreya, an antinomian form of Shiva closely associated with the cremation ground, who appeared to Baba Kina Ram atop Girnar Mountain in Gujarat. Considered to be the adi guru (ancient spiritual teacher) and founding deity of Aghor, Lord Dattatreya offered his own flesh to the young ascetic as prasād (a kind of blessing), conferring upon him the power of clairvoyance and establishing a guru-disciple relationship between them.
John Woodroffe, in his translation of the Mahānirvāṇatantraṃ from the original Sanskrit into English under the pen name "Arthur Avalon", may be the opening discourse of the archetype of "avadhūta" to the English reading public, as none of the avadhūta upanishads were translated amongst the collections of minor upanishads such as the Thirty Minor Upanishads (Aiyar: 1914). The Mahānirvāṇatantraṃ is an example of a nondualist tantra and the translation of this work had a profound impact on the Indologists of the early to mid 20th century. The work is notable for many reasons and importantly mentions four kinds of avadhūta.
The Brahmanirvantantra describes how to identify the avadhuts of the following types:
The Nath sampradaya is a form of avadhūta panthan. In this sampradaya, Guru and yoga are of extreme importance. The important book for the Nath is the Avadhuta Gita. Gorakshanath is considered the topmost form of the avadhuta-state.
One of the earliest hatha yoga scriptures, the Siddha Siddhanta Paddhati, contains many verses that describe the avadhūta. One stanza (VI.20) in particular refers to his chameleon-like capacity to animate any character or role. At times, it is said, he behaves like a worldling or even a king, at other times like an ascetic or naked renunciant."