крайъгълен камък angolul

cornerstone [cornerstones]▼(base stone)
noun
[UK: ˈkɔː.nə.stəʊn] [US: ˈkɔːr.nərˌstoʊn]

foundation stone▼(stone laid during construction)
noun
[UK: faʊn.ˈdeɪʃ.n̩ stəʊn] [US: faʊn.ˈdeɪʃ.n̩ ˈstoʊn]

keystone [keystones]▼(something on which other things depend for support)
noun
[UK: ˈkiː.stəʊn] [US: ˈkiːˌstoʊn]