be common knowledge

be common knowledge

To be something that is generally or widely known, whether or not it has been verified or officially recognized. The fact that a healthy diet and regular exercise are the best defense against disease is common knowledge at this point.
See also: common, knowledge

be common/public ˈknowledge

be something that everyone knows, especially in a particular community or group: What do you mean you’re surprised he’s leaving? I thought it was common knowledge that he was looking for another job!
See also: common, knowledge, public