The meaning of the adjective `phoney` in the novel The Catcher in the Rye

Holden likes the word phoney. It enables him to navigate his world. Holden operates that as long as people are "phoney", he has justification to dismiss the world in which he lives. As a result everything becomes ironic. The idea that others operate on deception and he alone sees the truth really becomes his identity; all the while Holden isolates himself from anyone and anything that might help him become a functional person.