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

Pettitte, who was the cornerstone starting pitcher of the Yankees' 1990s dynasty, is probably a good figure for Schlittler to emulate. —Jackson Roberts, MSNBC Newsweek, 3 Oct. 2025

These include new work requirements that are a cornerstone of Republican demands, under which certain adults would have to work or engage in qualifying activities to maintain Medicaid benefits. —Simon F. Haeder, The Conversation, 3 Oct. 2025

Over thirty years, he’s turned what started as a small, family-run business into a cornerstone of the community. —Maria Williams, USA Today, 3 Oct. 2025

Streaming has become a cornerstone of modern entertainment, but the landscape is shifting. —Adam Rumanek, Rolling Stone, 2 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