- the wedge-shaped piece at the summit of an arch, regarded as holding the other pieces in place.
- something on which associated things depend: the keystone of one's philosophy.
- Also called keystone sack. Baseball Slang. second base(def 1).
Origin of keystone
SynonymsSee more synonyms for keystone on Thesaurus.com
Examples from the Web for keystone
Congress is nearing a vote on the Keystone XL pipeline, and lawmakers made their cases for—and against—it Sunday.Fact-Checking the Sunday Shows: Jan. 4
January 5, 2015
Therefore, we should—you guessed it—develop the Canadian tar sands and build the Keystone pipeline.How Canadian Oilmen Pinkwash the Keystone Pipeline
December 28, 2014
From the looks of it, mistletoe is a keystone species and plays a crucial role in that forest ecosystem.Mistletoe is the Vampire of Plants
December 21, 2014
But if Clinton waded into the natural gas debate, she entirely avoided the Keystone one.Hillary Praises Fracking, Stays Silent on Keystone
December 2, 2014
They have made Keystone XL the poster child of their climate-change efforts.Why the Keystone XL Pipeline May Not Be Built
November 19, 2014
On this is the inscription: “Her loss was that as of a keystone to an arch.”Italy, the Magic Land
The keystone of the arch had been removed, the downfall of the whole must follow.Debts of Honor
In fact, not a few of us think that the Strathcona is the keystone of the Mission.A Labrador Doctor
Wilfred Thomason Grenfell
That is the keystone of American liberty—'malice toward none.'Spring Street
James H. Richardson
From the pavement to the keystone of its vault is but 132 French feet—about 150 English.Our Fathers Have Told Us
- Also called: headstone, quoin the central stone at the top of an arch or the top stone of a dome or vault
- something that is necessary to connect or support a number of other related things
Word Origin and History for keystone
"stone in the middle of an arch, which holds up the others," 1630s, from key (n.1) in figurative sense of "that which holds together other parts" + stone. Figurative sense is from 1640s. Pennsylvania was called the Keystone State because of its position (geographical and political) in the original American confederation, between northern states and southern ones. Keystone cops were the bumbling police in the slapstick silent movies produced by Keystone Company, formed by Canadian-born U.S. film director Mack Sennett (1884-1960) in 1912.