Image copyright Science Photo Library

It's 75 years since the death of Sigmund Freud, and the words and phrases he popularised are deeply ingrained in popular culture and everyday language. How did Freudian jargon become so widespread?

There's the Freud in textbooks. The bearded Viennese polymath who pioneered psychoanalysis. The Freud that academics never tire of arguing about.

Then there's the other Freud. The pub Freud. The one you might allude to when you mention dreams, or verbal slips, or someone fancying their mum. His relationship to the first Freud is tangential at best.

Eavesdrop on a conversation and it's likely that, sooner or later, a concept invented or popularised by the founding father of free association will pop up.

Oedipus complex. Denial. Id, ego and super-ego. Libido. Death wishes. Anal retentiveness. Defence mechanisms. Displacement. Phallic symbols. Projection. Transference. And, of course, Freudian slips.

It's not just Freud's terminology that is all over the popular lexicon. He's an adjective in his own right.

Some Freudian terms

Image copyright AP

The unconscious (or subconscious): Freud said that much of what we think is hidden from our waking minds, in our unconscious or subconscious; forbidden wishes and unacceptable thoughts can escape in a distorted way through dreams and "Freudian slips".

Oedipus Complex: Freud's term for the complex set of emotions which occur between children and their parents - named after the tragic figure of Sophocles's Greek drama, who - without knowing it - killed his father and married his mother

Id, ego and super-ego: A "structural" theory of the mind, which separates it into the id - the realm of uncoordinated and instinctual appetites, the super-ego which plays a critical and moralising role, and the ego, which aims a balance between the two.

The Freud Museum: Ideas In Psychoanalysis

"What would Freud think?" and "Ooh, that's a bit Freudian" are basically "nudge nudge, wink wink" for the sort of person who is very keen to let you know they went to university.

Other 20th Century intellectuals can't compete. Not Sartre or Chomsky or Einstein. Film reviews in red-top tabloids rarely name-drop Foucault or de Beauvoir.

But everyone knows what you're on about when you mention Freud. Or at least they think they do. The unconscious. Sexual repression. Dreams. Mummy and daddy issues.

"You don't have to read Freud to live in a world where Freud is important or to think in a Freudian way," says Stefan Marianski of the Freud Museum in London. All you need to do is consume mass popular culture produced from the mid-20th Century onwards.

Freud had the advantage of being an extremely good writer, who would illustrate psychoanalysis with reference to the work of great artists such as Shakespeare, Dostoevsky and Leonardo da Vinci.

Image copyright Getty Images Image caption Alfred Hitchcock's 1945 film Spellbound centres on psychoanalysis

But, believes psychologist Oliver James, author of Love Bombing, "The reason Freud became such a major cultural force is that he was brought into popular culture first through feature films." Starting with Alfred Hitchcock's 1945 psychoanalysis-themed thriller Spellbound, overt references to Freud have abounded in cinema.

Most notably, there's virtually the entire output of Woody Allen - as he says at the start of Annie Hall: "I never had a latency period". Then there's the father-son dynamic of The Empire Strikes Back and, indeed, Back to the Future. "It's basically the Oedipus complex," says Marianski. "The logic of Back to the Future is the same as Psycho, really."

And then you have the stream-of-consciousness novels of Virginia Woolf and James Joyce. Salvador Dali and the Surrealists. The Sopranos and Frasier. The 2011 film A Dangerous Method, starring Viggo Mortensen as Freud. Or indeed anything featuring a repressed memory, a dream sequence or a character with incestuous impulses.

Not that much of this is strictly - in the sense that academic scholars would use the term - Freudian. The gap between the pub Freud and what Freud actually wrote is often quite large.

Although much of his body of thought - not least around "infantile sexuality" - was seen as dangerously radical during his lifetime, the more challenging aspects of his work were rarely dwelt on by the mass media.

Image copyright Getty Images Image caption Lobster Telephone by Salvador Dali: Surrealist art was heavilly influenced by Freud's writings

"I think that most of us have only a vague - perhaps defensively vague - sense of what Freud is really saying, not least because in the field of popular culture his work has often been mediated to us in ways that water it down, make it palatable, reduce its insight, its complexity - and, I suppose, its difficulty - and turn it into a cosy and reassuring fantasy," says Dr Nicholas Ray, who lectures in Freudian thought at Leeds University.

Typically at the end of the film, the repressed memory is recovered, the heroine is granted self-knowledge and the audience gets a satisfying narrative conclusion.

But even if Freud is widely misunderstood and misrepresented, and the Oedipus complexes portrayed in TV dramas are quite different from the Oedipus complex set out in The Interpretation of Dreams, there is little denying his concepts remain the subject of widespread public fascination.

Image copyright ALAMY Image caption Freud's work - "mostly read in humanities departments today"

It's all the more remarkable given that much of what Freud wrote has been superseded by subsequent research, and that in some academic circles his theories have come under fierce attack - not least from feminists, who regard concepts such as penis envy as misogynistic, and accuse him of ignoring evidence that some of his patients had been victims of child abuse.

Freud still has his adherents - including Oliver James, who says his writings about dreams, the unconscious and the role of early childhood are still valid. But Marianski concedes Freud is "mostly read in humanities departments today" rather than by scientists.

Most of this will have passed the layman by, however. What's perhaps more significant, Marianski says, is that Freudian language was popularised during a particularly self-obsessed era.

Sigmund Freud 1856-1939

Image copyright ALAMY Image caption Viggo Mortensen as Sigmund Freud in the 2011 film, A Dangerous Method

Austrian neurologist and founder of psychoanalysis, regarded as one of most influential - and controversial - minds of the 20th Century

Born in Freiberg, Moravia (now Pribor in Czech Republic). Family moved to Leipzig and then settled in Vienna, where Freud studied medicine

Developed theory that humans have unconscious in which sexual and aggressive impulses are in perpetual conflict for supremacy with the defences against them

His major work The Interpretation of Dreams was published in 1900 in which dreams were explained in terms of unconscious desires and experiences

In 1923, he published The Ego and the Id, which suggested a new structural model of the mind, divided into the "id", the "ego" and the "superego"

In 1938, shortly after Nazi annexation of Austria, Freud left Vienna for London, where he died the next year

BBC History: Sigmund Freud

"From a historical perspective, he's part of a general movement where people start to look more into themselves," says Marianski. "There was a broad cultural shift in our culture - how you conceptualise the self?"

But there is much in Freud's writing that makes the continued prominence of his terms appear incongruous. In particular, his theories of repression belong very much to a pre-sexual revolution world.

"Now that young people seem to be at liberty to do whatever they want and talk about whatever they want, it's very interesting that Freud would still be very interesting to them," says James.

No doubt this won't stop people from picking and choosing Freudian terms as they see fit in the service of a great 21st Century activity - putting themselves and others on the proverbial couch.

As WH Auden wrote after Freud's death, "To us he is no more a person / now but a whole climate of opinion".

It's more elegant than "pub Freud".

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