white hat

noun

1

: one who is admirable and honorable

2

: a mark or symbol of goodness

could use a few more guys in white hats

—Robert Christgau

3

: a hacker who tests computer systems for possible vulnerabilities so that they can be fixed

Chu, 33, is part of a fraternity known as "penetration testers" or "ethical hackers," a group of experts who are hired to hack into computer systems or find other ways to gain access. These so-called "white hats" will spend days or weeks searching company systems to come up with recommendations for fortifying corporations against such threats.

—Greg Wiles

compare black hat

Word History

Etymology

from the white hats stereotypically worn by law-abiding characters in movie westerns

First Known Use

1965, in the meaning defined at sense 1