To discourage, inhibit, or deter something; to make something less enjoyable, pleasant, or fun; to have a subduing or deadening effect on something. (A variant of "put a damper on something.") The foul weather really put a dampener on our picnic yesterday. Without question, this tax scandal has put a dampener on the senator's likelihood of being re-elected. CDs quickly became the dominant format for music, but when digital formats arrived soon thereafter, it put a dampener on CD sales just as quickly.