[cor.ner.stone] n (13c) 1: a stone forming a part of a corner or angle in a wall; specif: such a stone laid at a formal ceremony
2: a basic element: foundation "a ~ of foreign policy"
[cor.ner.stone] n (13c) 1: a stone forming a part of a corner or angle in a wall; specif: such a stone laid at a formal ceremony
2: a basic element: foundation "a ~ of foreign policy"
Merriam-Webster English vocab. Английский словарь Merriam Webster. 2012