What is the definition of cornerstone? 1. a stone at the outer corner of two intersecting masonry walls 2. a stone in the exterior of a large and important building; usually carved with a date and laid with appropriate ceremonies 3. the fundamental assumptions from which something is begun or developed or calculated or explained "the whole argument â¦ Synonyms: foundation, fundament, groundwork, cornerstone, base, basis. Cornerstone. Usage: the whole argument rested on â¦ Synonyms for cornerstone in Free Thesaurus. Synonyms for cornerstone include basis, bedrock, foundation, keystone, base, linchpin, mainspring, mainstay, key and anchor. Find more ways to say cornerstone, along with related words, antonyms and example phrases at Thesaurus.com, the world's most trusted free thesaurus. Synonyms for 'cornerstone': feature, priority, element, basis, concern, key, essence, core, staple, burning issue/question, the ABC of something cornerstone (n.). Find more similar words at â¦ Learn more. Definition: the fundamental assumptions from which something is begun or developed or calculated or explained. How do you use cornerstone in a sentence? Antonyms for cornerstone. Synonyms (Other Words) for Cornerstone & Antonyms (Opposite Meaning) for Cornerstone. Cornerstone definition, a stone uniting two masonry walls at an intersection. Another word for cornerstone. What is the meaning of cornerstone? See more. cornerstone definition: 1. a stone in a corner of a building, especially one with the date when the building was made orâ¦. 17 synonyms for cornerstone: basis, key, premise, starting â¦ Another word for linchpin. Architectural term used twice in the New Testament ( Eph 2:20; 1 Peter 2:6) to speak of the exalted Jesus as the chief foundation stone of the church, the cornerstone on which all the building depends.The New Testament draws on two Old Testament passages about the coming Messiah ( Isa 28:16; Zech 10:4).In â¦ What are synonyms for cornerstone? Over time a cornerstone became a ceremonial masonry stone, or replica, set in a prominent location on the outside of a building, with an inscription on the stone indicating the construction dates of the building and the names of architect, builder, and other significant individuals.The rite of laying a cornerstone is an important â¦ Find more ways to say linchpin, along with related words, antonyms and example phrases at Thesaurus.com, the world's most trusted free thesaurus.