Gaslighting is a slang word for making someone question their sanity or their powers of reasoning.
When someone suggests that you are losing your mind (that may not be his real intention) ... but he makes you question your mental health ... teases you that you are forgetful and you don't hear well and your eyes are failing you... and accuses you that you are oversensitive and over-emotional ... that is the start of the vicious cycle of gaslighting.
The gaslighter often tricks you to make you uncertain about what is real and what is not. So when he says, pointing to the sky, "Look ... what was that ... and you said 'it is an airplane" and he insists "that was Superman," he was there to confuse you.
He was there invalidating what you saw ... contesting your feelings ... and in some part challenging your point of view.
The origin of the phrase began when a stage play was performed under the same title, GAS LIGHT. It is a story of a husband trying to drive his wife crazy by dimming the lights (which were powered by gas) in their home, and then he later denies that the light changed when his wife points it out.
Back to the topic ... people who gaslight feed you with lies, and the victim is aware that they are being lied to. The gaslighter's main concern here is how they were able to inject some kind of doubt into the person, doubting their REALITY when the incident is crystal clear and lucid, and they have seen everything en toto and heard enough.
Telling the victim their eyes and ears are not reliable is the start of the abusive template, and when the victim shows signs that they are wobbling in their position, especially with what they saw and heard, gaslighting is up for a good start.
I know of somebody who is quite savvy with gaslighting as a child (although I doubt if he knew what he was doing ... he was only seven then.) He woke up one December morning ... and I said: "Where are you going?" and he told me that he was going to attend and serve in the MASS."
Doubting what he is up to, I also went to church just to find out. I personally chose the seat in the last pew. He was not serving in the mass (I can see the acolytes in front from where I sit) ... and then I heard a familiar laughter at the back of the church ... it was him together with his friends. The REALITY was ... he woke up early to meet with his friends, and not because he became a holy convert that morning.
He told me lies ... and what was worse was ... he believed his lies. He looked me in the eyes, without batting an eyelash despite the blatant lies ... he maintained his claim that he served in the mass.
Pwede ba yon? Nagiging acolyte siya that morning pero hindi ko siya nakita sa harap ng altar ... kundi sa pintoan ng simbahan?
Bakit hindi na lang aakuin na sigi na nga ... nahuli mo ako. I woke up this early to be with my friends. Bakit kailangan paglaruan pa ako at questionin kung ano ang nakita at narinig ko?
And why do I have to question my sanity or my visual and hearing acuity .... or ask myself, was I dreaming (eh maliwanag pa sa tanghaling tapat ang chronology ng mga pangyayari??
At ako naman bakit kailangan maniwala ako sa sinabi niya ... eh ang nakita at narinig ko ay taliwas lang naman sa kung ano ang gusto niyang paniwalaan ko at kung ano ang gusto niyang palabasin.
And here's the twist of the story: I don't know what gaslighting was back then. But despite seeing that he was there at the back of the church with friends, I did not see him in front of the altar, either.
The REALITY was he did not ... but he succeeded in making me let go of the story by making me doubt and question my REALITY ... my sanity ... and my senses! Was I dreaming ... I painfully asked myself while rubbing my eyes (or in Tagalog, namamalik-mata ba ako?)
Having earned more units in General Psychology, Abnormal, Cognitive, Developmental, and Physiological Psychology, I taught Mental Hygiene and Psychiatry at the university and followed up with students in Psychiatric hospitals ... I can't believe a seven-year-old child has done that number to me.