To gaslight
Meaning
To manipulate someone by psychological means into doubting their own sanity or perception of reality.
Origin
The term 'gaslight' entered popular consciousness thanks to the 1938 play Gas Light and its subsequent film adaptations. In the story, a manipulative husband systematically dims the gaslights in their home, rearranges furniture, and makes other subtle changes, all while denying these events occur. He insists his wife is imagining things and losing her mind. This insidious form of psychological torment, where a victim's reality is distorted by someone else's deception, gave the phrase its enduring power as a descriptor for this specific type of abuse.