A bhikkhu, literally an almsman, is a fully ordained Buddhist monk, bound by the rules of the Vinaya; a bhikkhunī is a fully ordained nun. The Buddha founded the order of monks first and, according to tradition, the order of nuns at the request of his aunt Mahāpajāpatī.
Bhikkhu
A Buddhist monk: one who lives by alms under the monastic discipline; a nun is a bhikkhunī.
Also: Bhikshu, monk