LEARNit Dictionary
keystone
noun
/ˈkiːstəʊn/
UK
/ˈkiːstəʊn/
US
1
the central stone at the top of an arch that keeps all the other stones in position
سنگ کلید, سنگ تاج, سنگ تاج طاق
2
the most important part of a plan or argument that the other parts depend on
بخشکلیدی, عنصرمحوری, رکن اصلی
Changes to the welfare system are the keystone of the government’s reforms.