(3 syl.) or Nepenthes, a drug to drive away care and superinduce love. Polydamna, wife of Thonis (or Thone, 1 syl.), King of Egypt, gave nepenthe to Helen (daughter of Jove and Leda). Homer speaks of a magic potion called nepenthe, which made persons forget their woes. (Odyssey, iv. 228.)
That nepenthes which the wife of Thone In Egypt gave the Jove-born Helena.
Milton: Comus, 695, 696.
The water of Ardenne had the opposite effect.
Source: Dictionary of Phrase and Fable, E. Cobham Brewer, 1894
More on Nepenthe from Infoplease: