Lewis Short
(adjective) : grātŭlātōrĭus, a, um, gratulor
* 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.
Charlton T. Lewis, Charles Short, A Latin Dictionary