pleading. When a tenant in any real action, tenant by the curtesy, or tenant in dower, in his answer and plea, vouches any one to warrant his title, or prays in aid another who has a larger estate, as of the remainder-man or reversioner or when a stranger to the action comes and prays to be received to save his estate; then that which the defendant alleges against it, why it should not be admitted, is called a counterplea.