WordNet (r) 3.0 (2006):
Dutch uncle n 1: a counselor who admonishes frankly and sternlyMoby Thesaurus II by Grady Ward, 1.0:
20 Moby Thesaurus words for "Dutch uncle": Polonius, admonisher, adviser, backseat driver, buttinsky, confidant, consultant, counsel, counselor, expert, guide, instructor, kibitzer, meddler, mentor, monitor, nestor, orienter, preceptist, teacher