transcription, транскрипция: [ ˈkē-ˌstōn ]
noun
Date: circa 1637
1. : the wedge-shaped piece at the crown of an arch that locks the other pieces in place — see arch illustration
2. : something on which associated things depend for support
determination, a keystone of the puritan ethic — L. S. Lewis
3. : a species of plant or animal that produces a major impact (as by predation) on its ecosystem and is considered essential to maintaining optimum ecosystem function or structure