unknown quantity

Idioms and Phrases

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.

Example Sentences

Still an unknown quantity: where Rockne S. O'Bannon's Cult will end up on the schedule.

From The Daily Beast

But while Akerson may be an unknown quantity in Detroit, he is well-known to Whitacre.

From The Daily Beast

Idly his pen traced upon the paper in front of him a large X, the sign of the unknown quantity.

From Project Gutenberg

Concerning farming, it is an unknown quantity here, as we in Australia understand it.

From Project Gutenberg

It seemed to her, in those days and afterward, that Allen symbolized the unknown quantity in all the problems that absorbed him.

From Project Gutenberg

In a case detailed by Casper, in which a boy drank an unknown quantity of acid, death took place in seven hours.

From Project Gutenberg

In most small towns, and especially in farm houses, a furnace is an unknown quantity.

From Project Gutenberg

Related Words

• also-ran
• long shot
• sleeper
• underdog