Someone inside an organisation who tells the public, the press, or the authorities that the organisation is doing something dishonest, dangerous, or illegal. The key point is that the person is on the inside — an employee, an official, a member. An outsider who reports a company is just a complainer or a reporter; only an insider can be a whistle-blower, because only an insider is breaking loyalty to tell. That is why the word carries so much feeling: to their bosses they are a traitor, to the public they are often a hero. Many countries, including Taiwan, have laws meant to stop companies firing them, though in practice whistle-blowers often lose their jobs anyway. Written three ways — whistle-blower, whistleblower, whistle blower — with the one-word spelling now the most common in news writing. The verb is 'blow the whistle on someone/something'.