To ruin or detract from the effect of someone’s accomplishment by anticipating or copying it. This term originated in the early eighteenth-century theater, and the story behind it has been told by numerous writers. John Dennis (1657–1734), a critic and playwright, had devised a “thunder machine” for his play Appius and Virginia (1709); it consisted of rattling a sheet of tin backstage. The play failed, but a few nights later the same effect was used in a production of Macbeth, which Dennis attended and which prompted him to say, “They steal my thunder!” The term was subsequently used for similar situations and remained current long after its origin had been forgotten. Almost synonymous is the much newer to steal the show, meaning to outshine everyone else in a performance or at some event. It dates from the first half of the 1900s. The steal portion of this term implies that one is taking attention away from all the others.