Pushing the envelope

Meaning:	To approach or exceed known performance boundaries.
Example:	Your performance at work is not exactly pushing the envelope.
Origin:	This expression comes out of the US Air Force test pilot program of the late 1940's. The envelope refers to a plane's performance capabilities. The limits of the planes ability to fly at speeds and altitudes and under certain stresses define what is known as its performance envelope. It's an "envelope" in the sense that it contains the ranges of the plane's abilities. "Pushing the envelope" originally meant flying an aircraft at, or even beyond, its known or recommended limits. Thanks to Kensmark A safe bet is that many who pushed the envelope crashed. The expression was popularized by Tom Wolfe in his book "The right stuff" (1979) and later the movie of the same name.

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