Container having a child-proof, cup-shaped closure

A container (1) and child-resistant cap (10), said container (1) having an opening surrounded by an outwardly extending cylindrical neck (2), said neck having a single external thread groove (4) extending over at least one full rotation around said neck (2) for interaction with a radial projection (15) on an internal circular side wall (11) of said cap (10), whereby said thread groove (4) has a given width with a first side wall (4A) facing said container (1) (1) and a second side wall (4b) with a blocking device (7, 8), said second side wall (4b) being in frictional engagement with the projection (15) due to a compression of a packing (14) between said cap (10) and said neck (2) when said cap (10) is screwed onto said container neck, the width (b) of said thread groove (4) on a last portion of the rotation which last portion is closest to the container (1), is expanded in axial direction in relation to the width (a) of the remaining outermost portion of said thread groove (4), and in that a passage between said expanded portion and said remaining portion of said thread groove (4) is configured as a stop (7, 8) adapted to catch the projection (15) which lies freely in said thread groove (4) when said compression of said packing (14) is released due to unscrewing said cap (10), if said cap (10) is not pulled away from said container (1) in such a way that said projection (15) lies against said first side wall (4a).