Lewis Short
Lēthē | Lēthaeus, a, um (noun F) : Λήθη (forgetfulness)
* The river Lethe, in the infernal regions, from which the Shades drank and obtained forgetfulness of the past: pocula Lethes,Ov. P. 2, 4, 23: da mihi hebetantem pectora Lethen,id. ib. 4, 1, 17: soporifera,id. Tr. 4, 1, 47: immittere Lethen Stygiam alicui in viscera,i. e. forgetfulness,Luc. 5, 221: aqua Lethes, i. q. soporifera,Ov. M. 11, 603.— Hence
* Adj., of or belonging to Lethe, Lethean.
* Lit.: ratis,Tib. 3, 5, 24: amnis,Verg. A. 6, 705: stagna,Prop. 4 (5), 7, 91.
* Transf.
* Of or belonging to the infernal regions: Lethaei dii,Luc. 6, 685: tyrannus,i. e. Pluto,Col. 10, 271: Lethaea vincula abrumpere alicui,to bring one from the Lower World back to life,Hor. C. 4, 7, 27: janitor,i. e. Anubis,Stat. S. 3, 2, 112.
* That produces sleepiness or forgetfulness, Lethean: Lethaeo perfusa papavera somno,Verg. G. 1, 78: ros,id. A. 5, 854: papavera,id. G. 4, 545: sucus,Ov. M. 7, 152: amor,faithless love,id. R. Am. 551: nox,id. A. A. 3, 648.
Charlton T. Lewis, Charles Short, A Latin Dictionary