Nuns are solemnly professed religious sisters who live in a monastery, usually called an Abbey. Please note that Nuns are NOT Sisters. Sisters in the Catholic Church are religious women who take perpetual or simple promises, and usually live in a convent, teaching or nursing.
the fear of nuns is called "monachousaphobia"
A gathering of nuns is called a nunnery. Or a convent.
Nuns
Those who helped slaves escape to freedom were called abolitionists or conductors on the Underground Railroad. They provided shelter, food, and safe passage to those seeking to escape slavery in the United States.
Girls who were training to be nuns would be postulants when they start, and then novices. The Catholic Orders do not allow boys to be nuns or sisters.
Nurses are NOT typically called "sister or sisters", and would likely be seen as a put down in the US. However, many Nuns train to be nurses. Because they are Nuns, they are called Sisters.
Mary founded an order of nuns called the Sisters of St Joseph of the Sacred Heart.
Sisters of Charity
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Yes; they are called "Brides of Christ".
slag o'clock
Nuns have always lived in monasteries. They are sometimes called an Abbey, but the Abbey strictly refers to the Church, while "monastery" refers to the entire complex. "Monastery" can refer to a place where Nuns live, or where monks live. The archaic term for where Nuns live and work was "Nunnery."