ND -
The term is from the movie "Gaslight" with Charles Boyer and Ingrid Bergman.
They portrayed a married couple, but the husband kept doing things to the wife to make her believe that she was incompetent and basically losing touch with reality. (such as turning down the gas lighting in the home, when she thought she had turned them on)
Very good film. "Oh Paula..." he would say to her, with his French accent, whenever she was becoming confused or was losing it. He was a bastard to her!
The term "gaslighting" would refer to someone who is trying to make another look bad in the eyes of others....such as incompetent or perhaps unstable.
Hope this helps.
gg

I love that movie.

Thanks. I had no idea and I never saw the movie. No I get it.