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.

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Etymology

Origin of known quantity

First recorded in 1975–80

Example Sentences

As such, Warsh is a known quantity in upper-echelon social, political, and economic circles.

From Barron's • Feb. 2, 2026

Now a known quantity, Saints reduced their kicking to Caluori to deal with the breakout star's freakish aerial ability, while the teenager struggled to get the ball in hand to show his running power.

From BBC • Oct. 27, 2025

He is, in other words, a known quantity.

From Slate • Jan. 9, 2025

By the time the Minnesota coalition began its push in the legislature last session, it was a known quantity, said Joe Hobot, president of the American Indian OIC, one of the coalition members.

From Seattle Times • Aug. 8, 2023

This can be determined by a direct calibration, by inserting a known quantity of water at a known temperature and observing the contraction, or weighing the mercury drawn into the apparatus.

From Encyclopaedia Britannica, 11th Edition, Volume 5, Slice 1 "Calhoun" to "Camoens" by Various