Can we clarify the definition of gaslighting?

I ask this not to challenge anyone's experience but because I myself often get confused about this term ...

Does it apply any time two people have a different view on an interaction or incident?

Or is it more specific to when someone intentionally does something to confuse, belittle, or hurt you and then tells you it's "all in your head" and then get you confused about your own perception of reality... ?

What is the difference between (s)he said/(s)he said vs gaslighting? how do I separate that from real cognitive distortions?

Again I'm asking for my own understanding. (This is bit off topic... sorry) My ex would accuse me of gas-lighting her but she is the one who would call me "crazy" and a "liar" whenever we would fight. She would make HUGE assumptions and grand statements about my intentions, yet I could never get a word in on my own memory of what happened because as soon as I would try to explain my own perception on an incident, I was accused of "lying" and "making **** up."

My therapist says this has to do with intention and control. My Ex was trying to control and dominate me and make me question my own reality. The irony, of course, was that my ex was a psychologist that specialize in social justice so she had the vocabulary and skills to really make me feel wrong.

ETA: I see that someone posted some links. Thank you