cornerstone

noun

cor·​ner·​stone ˈkȯr-nər-ˌstōn 

1

: a stone forming a part of a corner or angle in a wall

specifically : such a stone laid at a formal ceremony

2

: a basic element : foundation

a cornerstone of foreign policy

Synonyms

• base
• basis
• bedrock
• bottom
• footing
• foundation
• ground
• groundwork
• keystone
• root
• underpinning
• warp
• warp and woof

Examples of cornerstone in a Sentence

Officials held a ceremony to lay the cornerstone for a new library.

Trust is the cornerstone of their relationship.

Recent Examples on the Web

This has been a cornerstone moment in my career that will live forever. —Carly Thomas, HollywoodReporter, 20 Apr. 2025

Campbell is the best offensive lineman in the draft and will be a cornerstone player for the Patriots for the next decade, protecting Drake Maye. 5. —Pat Leonard, New York Daily News, 19 Apr. 2025

Deterrence must therefore remain the cornerstone of Western policy, and especially European strategy, at least in the near term. —Alexander Gabuev, Foreign Affairs, 17 Apr. 2025

Keeping the hitter off balance is the real cornerstone of Imanaga’s mechanical mastery of the art of pitching. —Bernie Pleskoff, Forbes.com, 17 Apr. 2025

Word History

First Known Use

13th century, in the meaning defined at sense 1

Rhymes for cornerstone

• acetone
• anglophone
• baritone
• bourguignon
• buspirone
• chaperon
• chaperone
• cobblestone
• collarbone
• cortisone
• dictaphone
• dithizone

Kids Definition

cornerstone

noun

cor·​ner·​stone ˈkȯr-nər-ˌstōn 

1

: a stone forming part of a corner in a wall

2

: something of basic importance

the cornerstone of our foreign policy