Definitive evidence of wrongdoing or guilt; conclusive proof of a crime or misdeed.
The phrase derives from the detective fiction trope where finding someone holding a recently fired gun (still smoking from the gunpowder) provided undeniable evidence of guilt. While the concept appeared in 19th-century literature, the exact phrase gained prominence during the Watergate scandal in the 1970s when it was used to describe incriminating evidence.
The phrase became permanently embedded in American political vocabulary during Watergate, when Representative Barber Conable used it to describe the need for definitive evidence against President Nixon. The visual metaphor is perfect because gunpowder smoke dissipates quickly, just as crucial evidence can disappear if not captured immediately.
Complete word intelligence in one call. Free tier — 50 lookups/day.