kill two birds with one stone

To kill two birds with one stone is an idiom that means to solve two problems or achieve two distinct objectives using a single action. It is a common expression used to emphasize efficiency, resourcefulness, and the optimization of effort. The phrase is believed to date back to the mid-17th century, with early variations appearing in the works of philosopher Thomas Hobbes, referencing the literal practice of hunting small game using a stone or slingshot.

For centuries, the idiom has been used neutrally as a 'dead metaphor'—a figure of speech where the original imagery is no longer actively visualized by the speaker or listener. However, in recent years, the phrase has been contested by animal rights organizations, such as PETA, and proponents of veganism. These critics argue that language involving violence against animals constitutes 'speciesism' and subtly normalizes harm toward non-human creatures. While most English speakers consider the phrase harmless, those seeking more inclusive or non-violent language often opt for alternatives that convey the same efficiency without the lethal imagery.

Example:
"By cycling to work, I can kill two birds with one stone: I save money on gas and get my daily cardio in."

Example:
"The software patch killed two birds with one stone by fixing the security vulnerability and speeding up the user interface."