An unpredictable person or thing, as in We don't know how the new pitcher will do—he's an unknown quantity. This expression comes from algebra, where it signifies an unknown numerical value. Its figurative use dates from the mid-1800s.
Words nearby unknown quantity
How to use unknown quantity in a sentence
While Faal and Njie are in U.S. custody, the whereabouts of the other survivors is unknown.The Shadowy U.S. Veteran Who Tried to Overthrow a Country|Jacob Siegel|January 6, 2015|DAILY BEAST
The police suspect that the other unaccounted for 643,000 bitcoins, were removed from customer accounts via an unknown party.Japanese Bitcoin Heist ‘an Inside Job,’ Not Hackers Alone|Nathalie-Kyoko Stucky, Jake Adelstein|January 1, 2015|DAILY BEAST
Former Gov. Jimmy Carter entered the 1976 Presidential campaign as a more or less total unknown.
Until recently, the hacker collective known as Lizard Squad was all but unknown.
First, we need to change the debate—to focus at least as much on the quality of resources as the quantity.
A native of Haarlem on Zandam, the date of her birth being unknown.Women in the fine arts, from the Seventh Century B.C. to the Twentieth Century A.D.|Clara Erskine Clement
The phloridzin test consists in the hypodermic injection of a small quantity of phloridzin.
In acute and chronic parenchymatous nephritis the quantity is usually very large.
They also seized the lake gunboats, took an entire Spanish garrison prisoner, and captured a large quantity of stores.The Philippine Islands|John Foreman
There are two forms of elasticity, one of quantity and the other of quality, both provided for in the act.Readings in Money and Banking|Chester Arthur Phillips