Gaslighting

Scene from Gaslight (1944) with Ingrid Bergman, Angela Landsbury, and Charles Boyer.

Gaslighting is a form of psychological manipulation where the abuser lies to the victim and then tells them that their observations are false. The term comes from an old movie where the gas lights were turned up and down and then when the victim noticed, she was told she was wrong. Done successfully, gaslighting makes its victims doubt their own perceptions and even their own sanity.