sleepwort

From Middle English slepwort, slepwourt, equivalent to sleep +‎ wort, after the mild sedative properties of lactucarium.

sleepwort (uncountable)

1. (rare) Synonym of lettuce (Lactuca sativa)

• “sleepwort”, in OneLook Dictionary Search.
• William Dwight Whitney, Benjamin E[li] Smith, editors (1911), “sleepwort”, in The Century Dictionary […], New York, N.Y.: The Century Co., →OCLC.