A gathering of nuns is called a nunnery. Or a convent.
Convent, Cloister, or Nunnery
Monastery is for priest and nunnery is for nuns
Armathwaite Nunnery was created in 1092.
Ilchester Nunnery ended in 1463.
Negodong Nunnery was created in 15##.
Iona Nunnery was created in 1203.
Nenang Nunnery was created in 1333.
Reading Nunnery was created in 979.
Chupzang Nunnery was created in 1665.
Cannington Nunnery was created in 1138.
Cannington Nunnery ended in 1536.