Gaslighting is the somewhat clunky gerund verb form of Gaslight -- a 1940s movie depicting a man set out to drive his wife into thinking she was going insane by means of manipulating her through the creation of a false reality. The term has slowly seeped from the psychological circles into the mainstream. It can describe any manipulation through willfully-induced disorientation. 

It may be applied at the wholesale level in the form of fake news. What is it that you can hold onto in the political world these days? Gaslighting would suggest an active perpetrator(s) with a private agenda and an unwary victim. Might the victim be an entire country? Of course it might. The means to do so looms large and promises to explode. 

Listen to this fifty-minute segment (link: Breaking News Radiolab, starting at mark 1:45) to get an idea of technology's potential to refract the world through your very own lying eyes. Software engineers are on the cusp of making audio/visual renderings entirely mutable and, from that, any sense of reality essentially virtual. What could possibly go wrong with that?     
A willfully-induced disorientation at the retail level is arguably at the crux of the systemic sexual assault phenomenon (link: We Are All Mad Here). Really. Could that hunk-a-hunk-of-burning-love movie mogul now known as Exhibit A ever have had his way without the power, the props, and those star-hinting promises? Then add the a-girl-can-get-confused assertion to keep a lid on the whole matter afterwards and you have classic gaslighting.

Let us reflect and share our own gaslighting examples whether at the personal level (it can be experienced in all directions and many different ways) or as witness perhaps to a mass delusion e.g. think perhaps, say, a financial bubble.