cornerstone
UK[ˈkɔːnəstəʊn]US[ˈkɔːrnərstoʊn]
n
a stone that forms the base of a corner of a building, especially one laid at a ceremony.
n
something of great importance that everything else depends on.
Morpheme Breakdown
corner
stone
corner
horn, projecting point
stone
rock, stone
Etymology
the word 'cornerstone' is a transparent compound from middle english, directly combining 'corner' and 'stone'. its primary, literal meaning refers to the foundational stone set at the corner of a building, crucial for determining its alignment and stability. this architectural importance provided a powerful metaphor. consequently, by the late 16th century, it began to be used figuratively to denote an indispensable and fundamental part or principle upon which a system, organization, or idea is built and depends. the logic of the word perfectly mirrors its function: just as a physical cornerstone supports a structure, the abstract cornerstone supports an endeavor.
Analysis
Structure: corner + stone
corner (from anglo-norman 'cornere', old french 'corniere', ultimately from latin 'cornu' meaning 'horn, projecting point'); stone (from old english 'stān' meaning 'rock, stone').
Examples
the chancellor declared that education would be the cornerstone of the legislative agenda.
the ceremony included the laying of the cornerstone for the new library.
mutual trust is the cornerstone of a strong partnership.