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 of cornerstone

• 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

Giving Washington a makeover, from the Kennedy Center to the triumphal arch, has been a cornerstone of his second term in office. — Caroline Linton, CBS News, 2 Nov. 2026

Accountability is certainly a cornerstone of democracy, but there’s no question this recall referendum effort has brought its share of drama, social media sparring and ill will to a community that has plenty of other things to contend with. — Denise Crosby, Chicago Tribune, 1 Nov. 2026

The Nets still need someone to establish himself as the cornerstone of their next contender. — C.j. Holmes, New York Daily News, 1 Nov. 2026

The Titans, on the other hand, are 1-6 and have traded away one of their franchise cornerstones. — Ryan Canfield Outkick, FOXNews.com, 29 Oct. 2026

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