white hat(redirected from a white hat)
A virtuous or morally-sound person, often such a character in a book or film. The white hats are working to apprehend the masterminds behind the heist.
n. a good guy; a hero. (From Western movies where you could tell the good guys from the bad guys by the color of their hats: white for good, black for bad.) He seems like a white hat, but he’s a worm.