Closures are described consisting of a lid or cap member (3) and a container member (1). These are inter-engageable with one another. The lid or cap member (3) has a skirt and the container member (1) has an upstanding rim, each of which is of generally polygonal (preferably square) shape. Located on each of the facing walls on each side of the polygonal shape are inter-engageable projections (13, 14). The inter-engaging surfaces of the projections run substantially in a plane perpendicular to the axis of the polygonal shape and are of relatively small angular extent about that axis. The material of one or both of the skirt and container portion is resiliently elastic. The closure may be assembled with an axial push, and removed by twisting. This can be assisted by camming surfaces (12, 14) on the skirt and container portion exterior on which can engage with one another when the lid or cap member (3) is placed on the container member (1) and which tend as the inter-engageable projections (13, 14) are brought into engagement to urge the lid or cap member (3) to rotate relatively to the container member (1) to achieve a maximum area of inter-engagement between those projections. The closure is of particular value for a baby or infant feeding bottle, where the lid may incorporate a teat (2).Linvention concerne des fermetures constituées dun élément de couvercle ou de capuchon (3) et dun élément de contenant (1). Ceux-ci peuvent être mis en prise lun avec lautre. Lélément de couvercle ou de capuchon (3) est doté dune jupe et lélément de contenant (1) a un bord droit, chacun étant généralement de forme polygonale (de préférence carrée). Des saillies (13, 14) pouvant être mises en prise les unes avec les autres sont situées sur chacune des parois se faisant face de chaque côté de la forme polygonale . Les surfaces dengagement mutuel des saillies sétendent sensiblement dans un plan perpendiculaire à laxe de la forme polygonale et sont de relativement petite étendue angulai
