When a person projects elements of their delusion(s) onto reality. This is often the reason why people hate or attack you for no reason.
Usage example:
Doctor: You tried to escape. You struggled with one of the attendants and hit your head on a door. Do you remember that?
Riker: Yes... now I do. But at first, I thought a Klingon cut me... with a knife...
Doctor: It's called (a) transposition. You're projecting elements from your delusions onto events that really happened.
This happened in an episode of Star Trek: The Next Generation.