Word forms: foundation stones
1. countable noun [oft with poss] A foundation stone is a large block of stone built into a large public building near the bottom. It is often involved in a ceremony for the opening of the building, and has writing on it recording this. [mainly British] ⇒ The Princess of Wales laid the foundation stone for the extension to the Cathedral.regional note: in AM, use cornerstone 2. countable noun The foundation stone of something is the basic, important thing which its existence or success depends on. [+ of] ⇒ ...these foundation stones of the future: education, training, research, development.
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