Donald Trump Jnr announced this week that his new book-shaped object, due out in the autumn, was Triggered: How the Left Thrives on Hate and Wants to Silence Us. That might seem a bit snowflakey coming from someone whose racist dad is literally the president, but how did “triggered” acquire the sense of “emotionally distraught”?

The word “trigger” for the lever of a gun or trap was originally spelled “tricker”, and came from the Dutch trekken, to pull. From 1930 “to trigger” an event, idea, or action was to act as a catalyst for it. In 1977, the American jazz cornet player Jimmy McPartland explained: “Before I improvise, I just listen, and that triggers me.” He did not mean that what he heard upset him so much he had to run from the room.

In psychology specifically, however, a “trauma trigger” means a stimulus that triggers recall of a traumatic event. Hence the growing popularity of “trigger warnings”, and the modern shorthand that something you are about to read or watch may be “triggering”. American conservatives love to say liberals are too “triggerable”, while doing nothing about the actual triggers on the assault weapons so beloved by US mass killers.