n.1.(R. C. Ch.) One of an order of Italian monks, established in 1524, expressly to oppose Reformation, and to raise the tone of piety among Roman Catholics. They hold no property, nor do they beg, but depend on what Providence sends. Their chief employment is preaching and giving religious instruction.
2.(R. C. Ch.) One of an order of nuns founded by Ursula Benincasa, who died in 1618.
References in classic literature ?
The Theatin father, your eminence's director, was sent for this evening; and he cannot come again to my lord till after to-morrow.
Introduce the Theatin father," said Mazarin, closing the curtains.
Guillot, Claude 1989 La Population du Sud de Borneo a la Fin du XVIIe Siecle d'Apres le Temoignage des Theatins.