Dog-whistle politics is political messaging employing coded language that appears to mean one thing to the general population but has an additional, different or more specific resonance for a targeted subgroup. The phrase is only ever used as a pejorative, because of the inherently deceptive nature of the practice and because the dog-whistle messages are frequently themselves distasteful, for example by empathising with racist or revolutionary attitudes. It is an analogy to dog whistles, which are built in such a way that their high-frequency whistle is heard by dogs, but is inaudible to humans.
The term can be distinguished from “code words” used by hospital staff or other specialist workers, in that dog-whistling is specific to the political realm, and the messaging referred to as the dog-whistle has an understandable meaning for a general audience, rather than being incomprehensible.
GOTTA READ ASAP: Dog Whistle Politics: How Coded Racial Appeals Have Reinvented Racism and Wrecked the Middle Class by Ian Haney López