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

• basis
• foundation
• bedrock

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

Tyrer also was the left tackle on the AFL All-Time Team and a cornerstone of three franchise AFL titles and the Super Bowl IV champions. —Kansas City Star, 17 Oct. 2025

The brittle cornerstone of a decades-old player-development system suddenly crumbled, bringing the rest of the city game down with it. —Luke Cyphers, Sportico.com, 17 Oct. 2025

The Classic Knit The cornerstone of fall dressing is the crewneck sweater–versatile, comfortable, and endlessly re-wearable. —Minty Mellon, Vogue, 17 Oct. 2025

Ryst highlighted a couple of French institutions that have embraced YouTube as a cornerstone of their digital strategy. —Lise Pedersen, Variety, 17 Oct. 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