Gaslighting is a colloquialism, loosely defined as manipulating someone into questioning their own perception of reality. The expression, which derives from the title of the 1944 film Gaslight, became popular in the mid-2010s. Merriam Webster cites deception of one's memory, perception of reality, or mental stability. In a 2022 Washington Post report, it was described as a "trendy buzzword" frequently used to describe ordinary disagreements, rather than those situations that align with the word's historical definition.