TIME: “Be back in a jiffy!”

We’ve heard it, and maybe said it. But unless we’re the superhero The Flash, we probably didn’t get back in a jiffy. It’s a real unit of time — 1/100th of a second. “The earliest technical usage was in the late 19th century by Gilbert Newton Lewis. He proposed a unit of time called the “jiffy” which was equal to the time it takes light to travel one centimeter in a vacuum,” according to the website for the Starbird Association.

What about a “New York minute?”

It references the fast-paced lifestyle of New Yorkers and the term was likely coined by Texans during the late ’60s, reported Gary Clothier, Mr. Know-It-All columnist, according to The Standard.

“It was said a New Yorker does in an instant what a Texan would do in a whole minute. A New York minute has also been described as the interval between a Manhattan traffic light turning green and when the guy behind you starts honking his horn,” wrote Clothier. 

How about “Once in a blue moon?” That means very rarely. Folklore says a second full moon in a month’s time is called a blue moon, and it doesn’t happen very often. Others say it was a saying in the 1600s that meant something was absurd, as the moon was never blue.

“Moment” is another expression that actually has a meaning in time — “A moment (momentum) is a medieval unit of time. The movement of a shadow on a sundial covered 40 moments in a solar hour, a twelfth of the period between sunrise and sunset. The length of a solar hour depended on the length of the day, which, in turn, varied with the season.”