lethe

noun

le·​the ˈlē-thē 

1

capitalized : a river in Hades whose waters cause drinkers to forget their past

2

: oblivion, forgetfulness

lethean

ˈlē-thē-ən  li-ˈthē- 

adjective often capitalized

Word History

Etymology

Latin, from Greek Lēthē, from lēthē forgetfulness; akin to Greek lanthanein to escape notice, lanthanesthai to forget — more at latent

First Known Use

14th century, in the meaning defined at sense 1