KEYSTONE


Meaning of KEYSTONE in English

/ ˈkiːstəʊn; NAmE -stoʊn/ noun

1.

( architecture ) the central stone at the top of an arch that keeps all the other stones in position

2.

[ usually sing. ] the most important part of a plan or argument that the other parts depend on

Oxford Advanced Learner's English Dictionary.      Оксфордский английский словарь для изучающик язык на продвинутом уровне.