Definition of copestone in English:

copestone

noun

  • old-fashioned term for coping stone
    • ‘For small erections may be finished by their first architect; grand ones, true ones, ever leave the copestone to posterity.’
    • ‘In the cathedral of Vienna, the architect of the fifteenth-century Chapel of St. Barbara doubled the effect by fashioning two instances of the hanging copestones supported by flying ribs - one in each of its two bays.’

Origin

Mid 16th century: from cope + stone.

Pronunciation

copestone

/ˈkəʊpstəʊn/