Actually the term came from the 1938 play Gaslight. The George Cukor film with Boyer/Bergman/Cotten wasn’t even the first filmed version of Gaslight. But I’m sure you know that.
I did not, I stand corrected. I will say that the first film is of course mostly unknown. The play, which was popular in England, had its title changed to Angel Street when it played on Broadway. So I'm going to have to go with this:
The term "gaslight" was popularized in the general public's' mind by the release of a major Hollywood movie in 1944. It was released during the war when Americans were starved for entertainment. There was an earlier English version made in 1940 by Thorold Dickinson. His one major film was his last, Hill 55 Doesn't Answer (which I have seen) had its prints pulled out of circulation in an arraignment to make way for the Hollywood remake. Both were based on a play which was popular in England, but had its title changed to Angel Street when it played Broadway.
Amazing trivia, there is only one actor still living from the original Hollywood movie, and it was her first. It's...you'll have to look that up yourself. One of my mother's biggest thrills was running into her at Vicente Foods in Brentwood, telling her she loved her since Gaslight, and the actress telling my mom she couldn't be old enough to seen it at the time.