E. Cobham Brewer 18101897. Dictionary of Phrase and Fable. 1898.
Lethe (2 syl.),
in Greek mythology, is one of the rivers of Hads, which the souls of all the dead are obliged to taste, that they may forget everything said and done in the earth on which they lived. (Greek lthe, latho, lanthno, to cause persons not to know.)