grātŭlātōrĭus

a, um, adj.

gratulor

I. congratulatory (post-class.): epistola, Capitol. Max. et Balb. 17: cena, Jul. Val. Rer. Gest. Alex. 3, 34 al.—Adv.: grātŭ-lātōrĭē, in a congratulatory manner: mirari, Aug. Conf. 8, 6.
Lewis & Short
A Latin Dictionary, 1879
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