known quantity

American  

noun

1. Mathematics. a quantity whose value is given: in algebra, frequently represented by a letter from the first part of the alphabet, as a, b, or c.

2. any factor, circumstance, etc., that is already accepted or familiar.

   Her honesty is a known quantity.

---

Etymology

Origin of known quantity

First recorded in 1975–80

Example Sentences

In each case, Riley has opted to keep the known quantity.

From Los Angeles Times

“These counterfeit pills represent a serious overdose risk to buyers who think they are getting a known quantity of a weaker drug,” said Chelsea Shover, assistant professor-in-residence of medicine at the David Geffen School of Medicine at UCLA.

From Seattle Times

“DeSantis has really worked the culture wars, really worked Fox News, and he is the known quantity right now to people who are being polled,” Republican consultant Susan Del Percio said.

From Washington Post

“To my mind, you are better defaulting to the ones where we know that they work and there’s a known quantity when it comes to their safety,” says Snape.

From Scientific American

Nielsen and Monisha Harrell both compared Bruce Harrell to President Joe Biden — a known quantity whom Democrats chose try to beat Donald Trump in 2020.

From Seattle Times