Definition
To speak disrespectfully or critically about someone, especially when they are not present, often with a tone of scorn or irreverence.
She dislikes being criticized publicly, especially having her name taken in vain behind her back.
During the meeting, he tried to take his opponent's name in vain with a contemptuous tone, but his colleagues found it inappropriate.
They took their neighbors' names in vain freely at the dinner table, showing a clear lack of respect.