The word "finked" is often used to describe someone who has betrayed a trust or broken a promise, especially to authorities or law enforcement. Synonyms for this word might include "ratted," "snitched," "informant," or "whistleblower." Other related words might include "traitor," "turncoat," or "backstabber." These words all suggest a sense of betrayal and lack of trustworthiness. In some cases, however, there may be positive connotations to the act of "finking," such as when someone reports an act of wrongdoing or crime in order to protect others or prevent harm. In these cases, words like "hero," "advocate," or "activist" might be more appropriate.