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

For the Speaker, the product of an unplanned pregnancy, religion has long been a cornerstone of his life. —Eric Cortellessa, Time, 7 Aug. 2025

Communication Now and in the future, clear, honest and empathetic communication must be a cornerstone of HR leadership. —Dr. Nara Ringrose, Forbes.com, 6 Aug. 2025

Two-factor authentication is a cornerstone of modern digital security, protecting banking, email, and many other kinds of accounts worldwide. —IEEE Spectrum, 5 Aug. 2025

Downtown office properties have long been a cornerstone of property tax revenue. —Kenneth R. Gosselin, Hartford Courant, 3 Aug. 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