Bottle or container closure for the precise addition of a contents constituent

A bottle or container closure for a precise addition of a contents constituent includes a lower part having internal threads for a leak-proof application for the bottle or container, in which the lower part of the closure includes, in a clearance area, a chamber that can be closed with a membrane liner opening toward the bottom of the closure, which has a dome-shaped top side that includes a penetrating pin projecting downwardly inside the dome-shaped top side. The dome-shaped top side can be pressed downwardly, via deformation, so that the projecting pin can be pressed through the membrane liner. A pouring spout is located adjacent the chamber on the lower part of the closure, which releases through suction, or pressure, on the bottle or container. A covering lid is hinged to the lower part of the closure and can be swung on the body of the closure, in which a plug or a sleeve is present on the bottom side of the covering lid, so that the pouring spout can be closed in a leak-proof manner by the swinging of the covering lide on the lower part of the closure.