whistle-blower
noun [ C ]
WORKPLACE (also whistleblower) ukusa person who works for a company or organization that tells an authority about something illegal happening within the company or organization:
Within many organisations a whistleblower is contemptuously regarded as a 'grass' or 'sneak'.
whistle-blowing
noun [ U ]
Local authorities should have clear procedures to encourage staff whistleblowing.
See also
gagging clause