Lewis Short
grātes (noun F) : (usually only in the nom. and
* Acc. plur.; in the abl. gratibus, Tac. A. 12, 37), f. gratus, thanks rendered (esp. to the gods: gratias agere being the usual form to human beings), thanksgiving: ut Ephesiae Dianae lauta laudes Gratesque agam,Plaut. Mil. 2, 5, 2: diis laudes gratesque agunt,Liv. 7, 36, 7; 26, 48, 3; cf. in the following the passages,Tac. A. 1, 69 and 12, 37: vobis (dis) grates ago atque habeo,Plaut. Pers. 5, 1, 4: grates deis immortalibus agere habereque,Liv. 23, 11, 12 Weissenb. ad loc.; cf. 23, 12, 7: dis populoque Romano grates agunt,id. 10, 25, 5; 45, 39, 12: grates tibi ago, summe Sol, vobisque, reliqui caelites, * Cic. Rep. 6, 9: grates dis agere,Liv. 5, 23, 3; 30, 17, 6; Tac. A. 13, 41; cf. also: nec esse, qui diis grates agendas censeant,Liv. 30, 21, 9: salsipotenti et multipotenti Jovis fratri ... laudes ago et grates gratiasque habeo, Plaut. Trin. 4, 1, 2: laudes et grates reversis legionibus habens,Tac. A. 1, 69; cf.: Agrippinam iisdem quibus principem laudibus gratibusque venerati sunt,id. ib. 12, 37: vobis, o fidissime civium atque amicorum, grates ago habeoque,Curt. 9, 6, 17: dexteram ejus amplexi grates habebant velut praesenti deo,Curt. 3, 16, 17; Tac. A. 1, 69 Draeger ad loc.: Tiberius egit grates benevolentiae patrum,id. ib. 6, 2: o decus Italiae, virgo, quas dicere grates Quasve referre parem?Verg. A. 11, 508: grates persolvere dignas Non opis est nostrae, Dido,id. ib. 1, 600: grates rependere,Stat. S. 3, 3, 155: quibus pro bene factis fateor deberi tibi Et libertatem et multas grates gratias (cf. above: grates gratiasque),Plaut. Poen. 1, 1, 6.—Sarcastically: at tibi pro scelere, exclamat, pro talibus ausis, Di .. Persolvant grates dignas et praemia reddant Debita!Verg. A. 2, 537.
Charlton T. Lewis, Charles Short, A Latin Dictionary