A bhikkhu is an ordained male in Buddhist monasticism. Male and female monastics are members of the Sangha.
Bhikkhus in Thailand
Japanese monks of Jōdo Shinshū, Sōtō, and Shingon Buddhism.
A Cambodian monk in his robes
A nun is a woman who vows to dedicate her life to religious service and contemplation, typically living under vows of poverty, chastity, and obedience in the enclosure of a monastery or convent. The term is often used interchangeably with religious sisters who do take simple vows but live an active vocation of prayer and charitable work.
Hildegard of Bingen and her nuns
Maria Johanna Baptista von Zweyer, Abbess of the Cistercian abbey of Wald
Three Sisters of Charity of St. Vincent de Paul in the Portal of a Church, by Armand Gautier