That's not the definition. Insider trading non-public information also needs to be material, and not given or received by someone in breach of duty to the company or stolen from the company.

Your definition would mean a cab driver would be insider trading if he overheard random speculation about a company that turned out to be true--that's not illegal. However, if the cab driver's passenger said, "hey, I'm an executive at at XYZ and I saw that we're acquiring FGH," that is insider trading three ways: the driver believed they were receiving confidential information, the executive breached his duty, and the executive caused stolen information to be traded. And an acquisition would of course meet the material test.