A dogwhistle is a rhetorical tool that is used somewhat like watermarking, with the purpose of hiding another meaning within a seemingly harmless statement as a signal to those in the know that the statement comes from "their side" and should be supported.
Dogwhistles are used by the alt-right to inform other alt-righters that a piece of rhetoric or an article or what have you is made by their side and needs spreading, not criticizing or attacking.
Noted dogwhistles include:
- (((Echoes))): these are just weird use of brackets to most people, but the alt-right use them to denote Jewish people and make antisemitic accusations of an individual being involved in some kind of sinister plot or conspiracy.
- Fren: this is a term that seems harmless that white supremacists use to refer to each other (and is an acronym meaning Far Right Ethno Nationalist). It originated in the subreddit known as r/frenworld which was a whole system of dogwhistles to bury white supremacist speech under seemingly childish babble.
The term comes from the fact that dogs can hear higher pitches than humans, which lead to the creation of seemingly silent whistles that humans cannot hear (much like the uninformed) but dogs are perfectly aware of.