1540s, from Medieval Latin anodynus "pain-removing, allaying pain," from Latin anodynus "painless," from Greek anodynos "free from pain," from an- "without" (see an-(1)) + odyne "pain," a word perhaps from PIE root *ed- "to eat" (source of Lithuanian edžioti "to devour, bite," edžiotis "to suffer pain;" see eat). In old slang, frequently a euphemism for "death;" as in anodyne necklace "hangman's noose."