/ Thesaurus / R Synonyms of river lethe Find synonyms for: Noun1. Lethe, River Letheusage: (Greek mythology) a river in Hades; the souls of the dead had to drink from it, which made them forget all they had done and suffered when they were aliveWordNet 3.0 Copyright © 2006 by Princeton University. All rights reserved. Related Content Daily Word Quiz: cautious Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language