a man who gives frank and direct advice to someone. (In the way an uncle might, but not a real relative.) I would not have to lecture you like a Dutch uncle if you were not so extravagant.He acts more like a Dutch uncle than a husband. He's forever telling her what to do in public.
A stern, candid critic or adviser, as in When I got in trouble with the teacher again, the principal talked to me like a Dutch uncle . This expression, often put as talk to one like a Dutch uncle, presumably alludes to the sternness and sobriety attributed to the Dutch. [Early 1800s]