Definition of gaslight, gaslighting ?

To mess with someone’s head by denying reality until they start doubting their own brain. In modern slang, it’s when a person, brand, or official acts like something obvious never happened, or says you’re “overreacting” to things everyone saw on video. It’s emotional manipulation with PR training.

“They changed the law, then said they never touched it—peak gaslighting from the Big Serious Party.”