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

If lawmakers don’t extend it, the cornerstone of the Pentagon’s legal argument will evaporate. — Eleanor Mueller, semafor.com, 21 Sep. 2026

The iconic, award-winning EGF Serum is the cornerstone of the BIOEFFECT line. — ABC News, 19 Sep. 2026

Projecting stability and an image of due processes has become a cornerstone of President Vladimir Putin’s Russia. — Zahra Ullah, CNN Money, 18 Sep. 2026

The charismatic Mamdani made the city’s affordability a cornerstone of his campaign that was fueled by social media. — Tracy Grant, Encyclopedia Britannica, 18 Sep. 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