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

One of the cornerstones of the Okra Project, for example, is the organization’s annual Holiday Grocery Assistance Fund, which provides Black trans people with cash for food. —James Factora, Them., 7 Nov. 2025

Philanthropy is a cornerstone of their work. —Abby Montanez, Robb Report, 7 Nov. 2025

But Trump for months has threatened to slash federal funding to the city and mount an outright takeover if Mamdani won — threats that became a cornerstone of Mamdani’s rivals’ campaigns against him. —Emma Burleigh, Fortune, 6 Nov. 2025

These results could pave the way for more efficient and durable solar tower systems, a cornerstone of next-generation renewable energy infrastructure. —Atharva Gosavi, Interesting Engineering, 4 Nov. 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