Hunter Code ("The Word") is a written language of symbols made by the Messengers so that the Imbued can communicate with each other; there is no known verbal component. Only Hunters can understand the code or, in many cases, even notice it at all. It is often merely overlooked by any supernatural creature or non-Imbued humans.
Each symbol usually has a one-word meaning attached, and some symbols are harder to understand depending on an Imbued's Creed. For example, an Avenger would have a hard time understanding the meaning behind the symbol for "Friendly monster", because they're not inclined to see a monster as anything other than a target. Visionaries are uniquely capable of creating new symbols. These are used to intuitively communicate their master-plan for the hunt or human society.
Another set of symbols is available to Waywards of sufficient Vision, symbols only members of that creed can understand. These symbols are incomprehensible to any other Imbued, let alone supernatural creatures; like the standard code, each symbol has one-word meanings attached. These symbols serve as the Wayward Creed Ability - by marking them on their skin, a Wayward can enhance their personal capabilities.
While visiting Haiti, Shaka74 noted that veve (voudou religious symbols) looked like the Word. He observed one symbol which he understood meant "death" and enforced the connection between veve and the Word.
A gallery of extant hunter symbols can be found in Hunter: The Reckoning symbols .