on the fly

Idioms  

1. In a hurry, on the run, as in I picked up some groceries on the fly. The transfer of this expression, which literally means “in midair or in flight,” dates from the mid-1800s.

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Example Sentences

The Show was created on the fly, based around a drum loop and the theme song to kids' TV show Inspector Gadget.

From BBC

The software company borrowers that fill OTF’s portfolio are exactly the sort of companies that now worry investors, as new artificial intelligence tools promise to let users create their own software on the fly.

From Barron's

Ukraine, though poorer, built a layered defense on the fly, finding cheap-but-effective solutions including truck-mounted machine guns, drone interceptors and electronic jamming alongside cheaper interceptor missiles and jet fighters.

From The Wall Street Journal

With its more expansive layout, open entrances, and large concourses, it can pose particular problems by forcing players to adjust on the fly.

From Los Angeles Times

Manny Farber said that when he was about 4 years old, his father demonstrated to him how a computer worked by writing a computer program on the fly that could count to 100 by fives.

From The Wall Street Journal