I think the word denotes mapping of client side data to the server side data. In frameworks like Meteor, if there some addition or deletion of data on the serve

I think the word denotes mapping of client side data to the server side data. In frameworks like Meteor, if there some addition or deletion of data on the server side, browser notices the changes and updates the page accordingly. In frameworks like Rails or Django, changes of data on server side doesn't update the client side page (unless you customize the app with ajax)