A dispensing closure for a system having an opening between an exterior of the system and an interior of the system where a fluent substance may be stored, said dispensing closure comprising: A. a closure body that 1) can be located at the system opening and that defines an inlet for communicating with the system, 2) has an upper end defining an aperture to accommodate the flow of a fluent substance through said closure body, and 3) said closure body includes a pair of abutments extending upwardly from said upper end; B. a locking member mounted on said closure body for rotation about a central rotational axis, said locking member having an intermediate flow passage for accommodating the flow of a substance through said closure body aperture, said locking member having 1) a locking position, and 2) an unlocking position rotated about said central rotational axis away from said locking position; and C. an actuator that 1) is rotatably mounted to said locking member for occluding said locking member intermediate flow passage to prevent flow of a fluent substance through said closure when said actuator is in a closed, non-dispensing position and for permitting flow of a fluent substance through said closure when said actuator is rotated to an open, dispensing position, 2) includes a dispensing flow passage that is in communication with said intermediate flow passage of said locking member when said actuator is in said open, dispensing position, and 3) includes a pair of downwardly extending abutments for confronting said pair of upwardly extending abutments extending from said upper end of said closure body when said locking member is in said locking position to prevent said actuator from moving into said open, dispensing position; wherein said closure body further includes a flexible wall surrounding and defining said aperture, said flexible wall is movable in a radial direction relative to said central rotational axis to seal against a portion of said locking member. A. a closure body that 1) can be located at the system opening and that defines an inlet for communicating with the system, 2) has an upper end defining an aperture to accommodate the flow of a fluent substance through said closure body, and 3) said closure body includes a pair of abutments extending upwardly from said upper end; 1) can be located at the system opening and that defines an inlet for communicating with the system, 2) has an upper end defining an aperture to accommodate the flow of a fluent substance through said closure body, and 3) said closure body includes a pair of abutments extending upwardly from said upper end; B. a locking member mounted on said closure body for rotation about a central rotational axis, said locking member having an intermediate flow passage for accommodating the flow of a substance through said closure body aperture, said locking member having 1) a locking position, and 2) an unlocking position rotated about said central rotational axis away from said locking position; and 1) a locking position, and 2) an unlocking position rotated about said central rotational axis away from said locking position; and C. an actuator that 1) is rotatably mounted to said locking member for occluding said locking member intermediate flow passage to prevent flow of a fluent substance through said closure when said actuator is in a closed, non-dispensing position and for permitting flow of a fluent substance through said closure when said actuator is rotated to an open, dispensing position, 2) includes a dispensing flow passage that is in communication with said intermediate flow passage of said locking member when said actuator is in said open, dispensing position, and 3) includes a pair of downwardly extending abutments for confronting said pair of upwardly extending abutments extending from said upper end of said closure body when said locking member is in said locking position to prevent said actuator from moving into said open, dispensing position; wherein said closure body further includes a flexible wall surrounding and defining said aperture, said flexible wall is movable in a radial direction relative to said central rotational axis to seal against a portion of said locking member. 1) is rotatably mounted to said locking member for occluding said locking member intermediate flow passage to prevent flow of a fluent substance through said closure when said actuator is in a closed, non-dispensing position and for permitting flow of a fluent substance through said closure when said actuator is rotated to an open, dispensing position, 2) includes a dispensing flow passage that is in communication with said intermediate flow passage of said locking member when said actuator is in said open, dispensing position, and 3) includes a pair of downwardly extending abutments for confronting said pair of upwardly extending abutments extending from said upper end of said closure body when said locking member is in said locking position to prevent said actuator from moving into said open, dispensing position;