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" (cf., from the same root, Lithuanian edžioti "to devour, bite," edžiotis "to suffer pain;" see eat). In old slang, frequently a euphemism for "death;" e.g. anodyne necklace "hangman's noose."
anodyne an·o·dyne (ān'ə-dīn')
n.
An agent that relieves pain.