(Or as an adjective, commonsense) What people in common would agree; that which they “sense” in common as their common natural understanding. Some use the phrase to refer to beliefs or propositions that in their opinion they consider would in most people’s experience be prudent and of sound judgment, without dependence upon esoteric knowledge or study or research, but based upon what is believed to be knowledge held by people “in common”. The knowledge and experience most people have, or are believed to have by the person using the term.