A bhikkhuni (Pāli) or bhikṣuṇī (Sanskrit) is a fully ordained female Buddhist monastic. Male monastics are called bhikkhus. Both bhikkhunis and bhikkhus live by the vinaya. Bhikkhuni lineages enjoy a broad basis in Mahayana countries like Korea, Vietnam, China, and Taiwan.

According to Buddhist scriptures, the order of bhikkhunis was first created by the Buddha at the specific request of his foster-mother Mahapajapati Gotami, who became the first ordained bhikkhuni, relayed via his attendant Ananda (who also urged for the Buddha's acceptance of it). The bhikkhuni order spread to many countries.

For a country or nation to be considered as truly Buddhist, the majority of the nation must be Buddhist and include at least a fourfold assembly of bhikkhus, bhikkhunis, upasakas and, upasikas.

According to Theravada tradition, the bhikkhuni order of nuns came to be five years after the bhikkhu order of monks.

Buddhism is unique among Indian Religions in that Buddha, as founder of a spiritual tradition, explicitly states in canonical literature that a woman is as capable of nirvana (enlightenment) as a man, and can fully attain all four stages of enlightenment in the Dhamma and Vinaya of the Buddha Sasana. There is no equivalent, in other traditions, of the Therigatha or Apadanas which record the high levels of spiritual attainment by women.

Ajahn Brahmavamso Mahathera (known to most as Ajahn Brahm), born Peter Betts in London, United Kingdom on 7 August 1951, is a Theravada Buddhist monk. Currently Brahm is the Abbot of Bodhinyana Monastery, in Serpentine, Western Australia, the Spiritual Director of the Buddhist Society of Western Australia, Spiritual Adviser to the Buddhist Society of Victoria, Spiritual Adviser to the Buddhist Society of South Australia, Spiritual Patron of the Buddhist Fellowship in Singapore, and Spiritual Patron of the Bodhikusuma Centre in Sydney.

Peter Betts came from a working-class background and went to Latymer Upper School. He won a scholarship to study Theoretical physics at Cambridge University in the late 1960s. After graduating from Cambridge he taught in high school for one year before traveling to Thailand to become a monk and train with the Ajahn Chah Bodhinyana Mahathera. Brahm was ordained in Bangkok at the age of twenty-three by the Abbot of Wat Saket. He subsequently spent nine years studying and training in the forest meditation tradition under Ajahn Chah.

Chatsumarn Kabilsingh (Dhammananda Bhikkhuni, b. October 6, 1944), ordained Bhikkhuni Dhammananda, is a Thai Buddhist nun. On February 28, 2003, Kabilsingh received full bhikkhuni (nun) ordination in Sri Lanka making her the first Thai woman to receive full ordination as a Theravada nun in Dharmaguptaka ordination lineage. She was ordained in Sri Lanka She is abbess of the only temple in Thailand where there are fully ordained nuns.

Chatsumarn Kabilsingh was born in 1944 to Voramai Kabilsingh and Kokiat Shatsena. Her mother, Voramai, was the first Thai woman to be fully ordained as a bhikkhuni. Chatsumarn Kabilsingh relates how her mother became a nun when she (Chatsumarn) was ten years old, but rather than leaving the home as most women do, Voramai turned her home into her temple. Chatsumarn received Buddhist instruction and training along with the nuns. She says that her father, Kokiat, was "the first Thai man I knew who strongly supported the revival of the Bhikkhuni Sangha in Thailand." Unusual for Thai women, Chatsumarn received a higher education. After high school, she received her B.A. in Philosophy from Visva Bharati University, her M.A. in Religion from McMaster University in Canada, and her Ph.D. in Buddhism from Magadh University in India. She married, has three sons and three grandchildren. She taught for over thirty years at Thammasat University in Bangkok, Thailand, in the Department of Philosophy and Religion. Dr. Chatsumarn Kabilsingh is a well-known author of many books on contemporary issues in Asian Buddhism, including Buddhism and Ecology and Women in Buddhism.