In C++, public means those members that are accessible from anywhere where the object is visible, private means that members are accessible only from within other members of the same class or from their friends. But in Qt, the difference in private slots and public slots seem not to exist.

noun. a narrow, elongated depression, groove, notch, slit, or aperture, especially a narrow opening for receiving or admitting something, as a coin or a letter. a place or position, as in a sequence or series: The program received a new time slot on the broadcasting schedule.