The suppression of words, images, or ideas that are deemed offensive or subversive.
Note: "Censorship ... happens whenever some people succeed in imposing their personal political or moral values on others. Censorship can be carried out by the government as well as private pressure groups. Censorship by the government is unconstitutional."
"Two fundamental principles come into play ... The first is “content neutrality”– the government cannot limit expression just because any listener, or even the majority of a community, is offended by its content. In the context of art and entertainment, this means tolerating some works that we might find offensive, insulting, outrageous — or just plain bad.
The second principle is that expression may be restricted only if it will clearly cause direct and imminent harm to an important societal interest. The classic example is falsely shouting fire in a crowded theater and causing a stampede. Even then, the speech may be silenced or punished only if there is no other way to avert the harm."
Source of quotes: https://www.aclu.org/documents/what-censorship