idioms: pushing the envelope

Pushing the envelope means testing limits and trying out new, often radical ideas.

The expression comes originally from mathematics and engineering, where an envelope is a boundary, but was popularized by test pilots (especially those depicted in Tom Wolfe’s book The Right Stuff).

In aircraft design and testing, the envelope is the whole set of limitations governing safe operation of the aircraft. The pilots testing new aircraft wanted to take them right to the limits of performance and, if possible, beyond. They did this partly to test the calculated limits and partly to see what would happen.

In some business circles, the expression pushing the envelope has become an annoying cliché, and you should probably avoid it—unless you’re a test pilot, of course.