dogwhistle

Noun

dog whistle (plural dog whistles)

1. A high-pitched whistle, generally inaudible to humans, used to train dogs.

   Synonyms:

   silent whistle, Galton's whistle

2. (figuratively) That which is understood only by a narrow demographic.
   • But like a lot of these cult comedies, Cabin Boy was a dog whistle few could hear, and critics and audiences dismissed it quickly and forcefully: It left theaters with grosses south of $4 million and earned Elliott a “Worst New Star” Razzie nomination, no doubt for the adenoidal voice common to all...2012, 22 March, Scott Tobias, AV Club Cabin Boyhttp://www.avclub.com/articles/cabin-boy,71269/
3. (derogatory, sometimes) A political allusion or comment that only a certain audience is intended to note and recognize the significance of; particularly in relation to controversial or extreme viewpoints.
   • On the lips of Premier Mike Harris, the term ‘special interest’ has the tone of epithet. It’s an all-purpose dog-whistle that those fed up with feminists, minorities, the undeserving poor hear loud and clear.1995 October 15, Jim Coyle, Ottawa Citizen, p a9/1

   Synonyms:

   codeword