1 : serving to alleviate pain
2 : not likely to offend or arouse tensions : innocuous
"Anodyne" came to English via Latin from Greek "anōdynos" ("without pain"), and it has been used as both an adjective and a noun ("something that relieves pain") since the 16th century. It has sometimes been used of things that dull or lull the senses and render painful experiences less so. Edmund Burke used it this way, for example, in 1790 when he referred to flattery as an "anodyne draft of oblivion" that renders one (in this particular case, the deposed king Louis XVI) forgetful of the flatterer's true feelings. In the 1930s, a newer second sense began appearing in our vocabulary. Now, in addition to describing things that dull pain, "anodyne" can also refer to that which doesn't cause discomfort in the first place.