keystone

American  

[kee-stohn] / ˈkiˌstoʊn /

noun

1. the wedge-shaped piece at the summit of an arch, regarded as holding the other pieces in place.

2. something on which associated things depend.

   the keystone of one's philosophy.

   Synonyms:

   linchpin, foundation, principle, basis

3. Also called keystone sack.  Baseball Slang. second base.

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keystone British  

/ ˈkiːˌstəʊn /

noun

1. Also called: headstone.   quoin.  the central stone at the top of an arch or the top stone of a dome or vault

2. something that is necessary to connect or support a number of other related things

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Etymology

Origin of keystone

First recorded in 1630–40; key ¹ + stone

Example Sentences

Truth Social isn’t an especially strong keystone of this operation.

From Los Angeles Times

Proponents hailed lions as a keystone species that enhances biodiversity and pointed out the affection they generate — from Los Angeles’ late, famed P-22 to the lion that recently strolled through San Francisco.

From Los Angeles Times

Morgan healthcare investor conference in San Francisco in mid-January, a keystone event at which companies often pre-announce guidance and earnings and roll out marquee acquisitions.

From Barron's

One can’t make a list like this without including the keystones of modern detective fiction.

From Los Angeles Times

The home became a keystone of Gehry’s work, and a symbol of rebellion against architectural polish and formality.

From Los Angeles Times

Related Words

• base
• cornerstone
• foundation
• fundament