Best def. of gaslighting I've come across

[an email]

I've defined gaslighting before as when no matter what you do or say people act like you're being weird. 

Here's another way of defining it I just came across:

"Mickey Kaus characterizes the approach as “gaslighting” — giving your opponent a legitimate reason to get angry, then turning around and pointing to their anger as evidence they’re unhinged, obsessed, [etc.]..."

Disingenuous bewilderment is a cousin to this behavior. 

It's often, probably usually, done unconsciously. Most people aren't calculating enough to do it consciously. It's a devil spirit thing. Often done to individuals who are rogue from the devil's kingdom. Or in the first stages of becoming so. Or obviously a lost cause hence it's done to try to destroy them. People engaged in spiritual warfare experience this. - C.