Lewis Short
(interjection) : ēiă (in MSS. also hēiă), εἴα.
* An expression of joy or of pleased surprise.
* In admiring an object, ah! ah ha! indeed! Plaut. Rud. 2, 4, 8; id. Men. 2, 3, 30; Ter. Heaut. 5, 5, 19; 3, 2, 10.
* Of impatient exhortation, ho! quick! come on! Plaut. Most. 3, 1, 71; Plin. Ep. 4, 29; Verg. A. 9, 38; Hor. S. 1, 1, 18; 2, 6, 23; in the combination: eia age,come then! up then!Verg. A. 4, 569; Stat. Ach. 2, 198; id. Silv. 1, 2, 266.
* In strong affirmation, Plaut. Ps. 1, 3, 40; id. Bacch. 1, 1, 43; and so ironically: eia credo,id. Capt. 5, 2, 9.
* With vero, ironically, expressing amused doubt of what has been said, pshaw! Plaut. Ep. 2, 2, 77; id. Mil. 4, 4, 5; id. Rud. 2, 3, 9; Cic. Rep. 3, 5.
Charlton T. Lewis, Charles Short, A Latin Dictionary