noun
tip-off; anonymous report; information
Refers to providing information, often anonymously, to authorities or media about wrongdoing or inside information. Commonly used in news and crime contexts.
警察にタレコミがあった。
There was a tip-off to the police.
内部告発のタレコミが新聞社に届
An anonymous whistleblower report reached the newspaper.
密告 is a more formal term for informing on someone, often with a negative connotation of betrayal. タレコミ is more casual and commonly used for anonymous tips to media or police.
内部告発 specifically refers to whistleblowing from within an organization, while タレコミ can come from anyone and is often anonymous.
Derived from the verb 垂れ込む (たれこむ), meaning 'to inform on' or 'to tip off'. The noun form タレコミ is a nominalization of the verb's continuative form.