slang A derogatory term for someone who notifies authority figures about illegal or prohibited activity or those who commit such activity; a snitch or tattler. Don't worry, boss—we'll send that squealer to the bottom of the Hudson in a pair of concrete boots.You're little brother is such a squealer, Tommy! If we do the slightest thing wrong, he goes and blabs about it to your parents!
squealer
1. n. an informer. (Underworld.) Some squealer let the cops know what was going to happen.
2. n. a pig; a piglet. They sent their squealers to market at just the right time.