Informer

1. v. One who informs a magistrate of violations of law; one who informs against another for violation of some law or penal statute.
2. v. One who informs, animates, or inspires.
3. v. One who informs, or imparts knowledge or news.

The word meanings were obtained from OPTED(The Online Plain Text English Dictionary), which is based on “The Project Gutenberg Etext of Webster’s Unabridged Dictionary” which is in turn based on the 1913 US Webster’s Unabridged Dictionary (See Project Gutenburg), as a text file.