https://en.wikipedia.org/wiki/Overton_window
The range of policies and ideas that are considered politically acceptable to the mainstream population at any given time. Named after Joseph Overton, a policy analyst, this concept illustrates how public opinion shapes what politicians can propose and support without appearing too extreme.
The window can shift over time as societal norms and values change, allowing previously radical ideas to become mainstream and vice versa. Essentially, it defines the boundaries of acceptable discourse in the political landscape. (Open Civics)