Cup-shaped shower jet outlet nozzle, comprising - a hollow chamber, - a lateral wall delimiting the hollow chamber transversely to a nozzle longitudinal axis (D L), and - a bottom delimiting the hollow chamber in the direction of the nozzle longitudinal axis on an outlet side, which bottom is made of an elastic material and in which a jet outlet opening structure (4 s) composed of one or a plurality of jet outlet openings and having an open initial configuration is provided, - wherein the bottom is designed, with the jet outlet opening structure thereof, under the effect of a shower fluid operating pressure in the hollow chamber, to deform in an elastically resilient manner and thereby to steadily increase an opening crosssection (Q S) of the jet outlet opening structure with increasing shower fluid operating pressure within a normal operating pressure range, characterized in that - the jet outlet opening structure (4 S) is spaced apart from the lateral wall, and the bottom on an inner side (3 I) and/or on an outer side (3 A) has a weakening pattern with a lesser wall thickness as compared to an adjacent region of the bottom, wherein the weakening pattern is designed to deform in an elastically resilient manner under the effect of the fluid operating pressure in the hollow chamber, and/or - the jet outlet opening structure (4 s) comprises at least one jet outlet opening having an opening radius (R O) increasing and decreasing alternatingly in the circumferential direction, while forming alternate bulge regions and recess regions, wherein the bulge regions each have a rounded shape with a respective minimum bulge curvature radius (K A) and the recess regions each have a rounded shape with a respective minimum recess curvature radius (K E), wherein the minimum bulge curvature radii and the minimum recess curvature radii are in a range between 0.01 mm and 1 mm, and/or wherein the minimum bulge curvature radii are in a size ratio between 0.3 and 2.5 to the minimum recess curvature radii, and/or - the jet outlet opening structure (4 s) comprises at least one jet outlet opening having a non-planar opening edge (8 n) which is undulated extending with an axial directional component (R A) pointing in a fluid outlet direction (F A) and counter to the fluid outlet direction relative to a plane (E B) of the bottom. - a hollow chamber, - a lateral wall delimiting the hollow chamber transversely to a nozzle longitudinal axis (D L), and - a bottom delimiting the hollow chamber in the direction of the nozzle longitudinal axis on an outlet side, which bottom is made of an elastic material and in which a jet outlet opening structure (4 s) composed of one or a plurality of jet outlet openings and having an open initial configuration is provided, - wherein the bottom is designed, with the jet outlet opening structure thereof, under the effect of a shower fluid operating pressure in the hollow chamber, to deform in an elastically resilient manner and thereby to steadily increase an opening crosssection (Q S) of the jet outlet opening structure with increasing shower fluid operating pressure within a normal operating pressure range, - the jet outlet opening structure (4 S) is spaced apart from the lateral wall, and the bottom on an inner side (3 I) and/or on an outer side (3 A) has a weakening pattern with a lesser wall thickness as compared to an adjacent region of the bottom, wherein the weakening pattern is designed to deform in an elastically resilient manner under the effect of the fluid operating pressure in the hollow chamber, and/or - the jet outlet opening structure (4 s) comprises at least one jet outlet opening having an opening radius (R O) increasing and decreasing alternatingly in the circumferential direction, while forming alternate bulge regions and recess regions, wherein the bulge regions each have a rounded shape with a respective minimum bulge curvature radius (K A) and the recess regions each have a rounded shape with a respective minimum recess curvature radius (K E), wherein the minimum bulge curvature radii and the minimum recess curvature radii are in a range between 0.01 mm and 1 mm, and/or wherein the minimum bulge curvature radii are in a size ratio between 0.3 and 2.5 to the minimum recess curvature radii, and/or - the jet outlet opening structure (4 s) comprises at least one jet outlet opening having a non-planar opening edge (8 n) which is undulated extending with an axial directional component (R A) pointing in a fluid outlet direction (F A) and counter to the fluid outlet direction relative to a plane (E B) of the bottom.