Other forms: insiders
An insider is somebody within a group who knows its secrets. An industry insider, insider knowledge, according to an insider.
In finance the word names a crime: insider dealing is trading on information the public does not have, and it carries a prison sentence. In journalism an insider is an unnamed source with real access.
1nouninsiderSomebody within a group who knows its secrets.
“According to an insider, the company is planning to close its London office.”
insider is a person.
From inside + -er.
Etymology from Wiktionary, CC BY-SA