Gaslighting is a term for a pattern of behaviour in which one person is made to doubt their own perception, memory, or judgement. The word comes from Patrick Hamilton’s 1938 play Gas Light, in which a husband secretly dims the house’s gas lamps and denies that anything has changed, leaving his wife questioning her own senses. The term has since moved far beyond the play and is now used widely in psychology, relationships, and everyday language. This entry is educational: it defines the term as it is used, not as a clinical assessment of any person or relationship.
What it looks like
As the term is commonly used, gaslighting involves repeated denial or contradiction of what another person experienced. Someone may insist an event never happened, claim a conversation went differently from how the other person remembers it, or dismiss the other person’s reactions as overreactions. The cumulative effect, when the pattern is sustained, is that the person on the receiving end begins to distrust their own recollection and judgement, and to rely on the other person’s version of events instead.
Why the term is debated
Gaslighting is also a contested term, and that is worth knowing. In clinical and research writing, it is not a formal diagnosis, and there is no single agreed definition. In everyday speech, the word is sometimes applied loosely to any disagreement, lying, or unpleasant argument, which stretches it beyond its original meaning of sustained reality-undermining. Psychologists and writers therefore tend to distinguish between a one-off denial or argument, which is common in conflict, and a repeated pattern that systematically undermines someone’s confidence in their own perception.
An everyday example
Two colleagues disagree about what was decided in a meeting. One says, “We never agreed to that,” though the other clearly remembers the agreement and has notes to match. If this happens once, it may be an ordinary memory dispute. The term gaslighting is generally reserved for a repeated version of this pattern: every disagreement is met with denial, the notes are dismissed as misread, and over time the second colleague stops trusting their own records and starts deferring to the first colleague’s account. It is the repetition and the erosion of confidence, rather than a single disagreement, that the term is meant to capture.