A Sadhu (Sanskrit: साधु, IAST: sādhu for male, sādhvī for female; also spelled saddhu) is a religious ascetic, mendicant or holy person in Hinduism and Jainism who has renounced worldly life. Sadhus are sometimes referred to as yogi, sannyasi or vairagi. The term sādhu denotes one who follows a path of sadhana, or spiritual discipline. While most sadhus are also yogis, not all yogis are considered sadhus.
According to tradition, a sadhu's life is dedicated to attaining moksha, liberation from the cycle of death and rebirth. This pursuit corresponds with the fourth and final ashrama, or stage of life, and is undertaken through meditation and contemplation of Brahman. Renunciation of worldly possessions, known as sannyasa, is central to the sadhu's way of living.
Outward markers often reflect this renunciation. In Hinduism, sadhus typically wear simple saffron-coloured clothing. In Jainism, mendicants are commonly seen in white robes, while some traditions practise nudity as a sign of complete detachment. A female mendicant in Hinduism and Jainism is generally referred to as a sadhvi, and in certain texts as aryika.
In Sikhism, a person who has attained the state of Brahmgiani may be regarded as a sadhu. However, the Sikh tradition does not endorse asceticism, celibacy or begging as religious practices, distinguishing the Sikh understanding of the term from its usage in Hindu and Jain contexts.
Adapted from the English Wikipedia article on Sadhu.