The river of forgetfulness: The Lethe is one of the five rivers of Hades; the others were the Acheron, the Cocytus, the Phlegethon, and the Styx.

Those who drank from the River Lethe immediately forgot everything that had happened to them.

The expression "waters of Lethe" or the word lethean has been used to imply forgetfulness and complete oblivion of the mind which overcame the souls who drank from this stream in the "Lower World".

A total loss of memory or a mental oblivion of what has happened in the past or complete forgetfulness: Lethe was also the name of the Greek spirit of forgetfulness and oblivion, with whom the river was often identified.

In Classical Greek, the word lethe literally means "oblivion", "forgetfulness", or "concealment".