Literally, kind usage of someone. The phrase “tender mercies” comes from the Bible’s Book of Psalms (25:6), “Remember, O Lord, thy tender mercies and they loving kindnesses.” Since at least 1900 or so the term has been used ironically, as in Stella Rimington’s At Risk (2004): “‘What would you have done if the guy had refused to give back the money?’ ‘Left him to your tender mercies,’ said Liz. . . . ‘We don’t do violence.’”

Acronym for tender loving care. In modern times this phrase is believed to have originated in a hospital or other sick-care setting, where it alludes to kind and solicitous treatment by nurses. From the mid-1900s on it caught on in a more general way, particularly among songwriters, according to wordsmith Nigel Rees, who found nearly a dozen songs with this title written between 1960 and 1983. Today the term, both spelled out and abbreviated, is applied to kind or gentle treatment for almost anything—a pet, person, plant, automobile, and so on. It has just about replaced the almost synonymous tea and sympathy, meaning special kindness shown to someone who is upset. This term was always most common in Britain, where a cup of tea is standard treatment in such situations. It gained currency as the title of a play by Robert Anderson and a motion picture based on it (1956) about a prep school boy’s affair with a teacher’s wife, but it has largely died out, at least in America.