An anodyne (Greek αν, loss, and οδυνη, pain: a cause which relieves pain) is a medicine that relieves or soothes pain by lessening the sensitivity of the brain or nervous system. Also called an analgesic (or colloquially a "painkiller").
The term has been applied incorrectly to various medications, such as narcotics, hypnotics, and opiates. True anodynes were applied externally to the part affected. Among those classed "simple" were onion, lily, root of mallows, leaves of violet, and elderberry.
Certain compound medicines were also called by this name, such as anodyne balsam, made of castile soap, camphor, saffron, and spirit of wine, and digested in a sand heat. It was recommended not only for easing extreme pain, but for assisting in discharging the peccant matter that occurred with the pain.
By extension, soothing or placating words are called anodyne.
In common parlance, it means innocuous - not likely to offend or arouse passion.