In plain words
Hebrew for “truly” or “so be it.” Said at the end of a prayer to make it your own.
The fuller definition
Hebrew for “truly” or “so be it.” Said at the end of prayers by the whole assembly, it makes the prayer the people’s own. Luther’s Small Catechism explains it as “Yes, yes, it is going to come about just like this.”
Where it comes from
Small Catechism, The Lord’s Prayer
In Sunday worship: The parts of a service, daily prayer, and the things you see in a church.