a person who criticizes or reproves with unsparing severity and frankness.
Origin of Dutch uncle
First recorded in 1820–30
Because Dutch is used here to describe someone manifesting the opposite of warm, affectionate, typically avuncular behavior, this term is sometimes perceived as insulting to or by the Dutch. See also Dutch.
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]