Stoolpigeon, a term used to describe an informant or a snitch, is often considered derogatory. However, there are several other synonyms that can be used to describe a person who provides information to the authorities. Some of the commonly used synonyms include "informant," "tipster," "rat," "squealer," "whistleblower," "turncoat," and "traitor." While some of these words carry negative connotations, others are more neutral and may be used in a less pejorative manner. The choice of synonym depends largely on the tone and context of the conversation or piece of writing where the term is used.