Public Intellectual Meaning

(idiomatic) A well-known, intelligent, learned person whose written works and other social and cultural contributions are recognized not only by academic audiences and readers, but also by many members of society in general.

Example: 2001 June 13, Chris Hedges, "Public Lives: Watching Bush's Language, and Television," New York Times (retrieved 24 Oct 2012):
  "I have always taken the role of public intellectual very, very seriously," said Mark Crispin Miller, 51, a professor of media ecology at New York University. "A public intellectual is someone who engages in intellectual pursuits, airs intellectual concerns in a way the broad, literate public can understand. The tradition thrives in Europe, but the American public does not have the same expectation of its intellectuals."
2005, Louis Mazzari, "New Introduction" to Preface To Peasantry (1936) by Arthur Franklin Raper, ISBN 9781570036033, p. xvii (Google preview):
  As a sociologist, Raper concerned himself with everything from the legal impediments African Americans faced to the way blacks and whites arranged themselves around the hot stove in a small-town general store. He was among the first generation of southern public intellectuals, an engaged academic in a region where anti-intellectualism had a long and healthy tradition.
2012 June 11, Nate Rawlings, "Paul Fussell" (Obituary), Time:
  After years of teaching 18th century British literature, in 1975 he crossed from academic to public intellectual with The Great War and Modern Memory, a seminal book examining how World War I, by its scope and immense carnage, caused a disillusionment that plagued Western society for decades.