The invention contemplates selectively openable closure means that is tamper-proof, in the sense that a correct sequence of two deliberate and independent movements of lockable closure elements is necessary in order to achieve access to the contents of the bottle or the like which is protected by the closure. The specific construction that is described involves a bottle member with a threaded neck and a closure-cap member. The latter comprises telescoped relatively rotatable parts, the inner of which threads to the neck, and the outer of which is for manual operation. The parts of the closure-cap member have a limited axial lost-motion connection, and deformable means on one of the tubular members has cammed engagement with a coacting part of the other tubular member during the course of lost-motion displacement. Thus, lost-motion displacement must occur before the bottle can be uncapped.