Slang rarely has staying power. That is part of its charm; the young create it, and discard it as soon as it becomes too common. Slang is a subset of in-group language, and once that gets taken up by the out-group, it’s time for the in-crowd to come up with something new. So the long life of one piece of American slang, albeit in many different guises, is striking. Or as the kids would say, “Dude!”

Though the term seems distinctly American, it had an interesting birth: one of its first written appearances came in 1883, in the American magazine, which referred to “the social ‘dude’ who affects English dress and the English drawl”. The teenage American republic was already a growing power, with the economy booming and the conquest of the West well under way. But Americans in cities often aped the dress and ways of Europe, especially Britain. Hence dude as a dismissive term: a dandy, someone so insecure in his Americanness that he felt the need to act British. It’s not clear where the word’s origins lay. Perhaps its mouth-feel was enough to make it sound dismissive.

From the specific sense of dandy, dude spread out to mean an easterner, a city slicker, especially one visiting the West. Many westerners resented the dude, but some catered to him. Entrepreneurial ranchers set up ranches for tourists to visit and stay and pretend to be cowboys themselves, giving rise to the “dude ranch”.

By the 1950s or 1960s, dude had been bleached of specific meaning. In black culture, it meant almost any male; one sociologist wrote in 1967 of a group of urban blacks he was studying that “these were the local ‘dudes’, their term meaning not the fancy city slickers but simply ‘the boys’, ‘fellas’, the ‘cool people’.”

From the black world it moved to hip whites, and so on to its enduring associations today—California, youth, cool. In “Easy Rider” (1969) Peter Fonda explains it to the square Jack Nicholson: “Dude means nice guy. Dude means a regular sort of person.” And from this new, broader, gentler meaning, dude went vocative. Young men the world over seem to need some appellation to send across the net at each other that recognises their common masculinity while stopping short of the intimacy of a name. It starts in one country or subculture, and travels outwards. Just as the hippies gave us “man”, and British men are “mate” to one another, so, by the late 1970s or early 1980s, “dude” was filling that role. And all three words are as likely to go at the start of the sentence as the end.

Sean Penn’s surfer-stoner in “Fast Times at Ridgemont High” (1982) says “Make up your mind, dude.” By 2000, the vocative use and whiff of stoner culture was firm. The title line of “Dude, Where’s My Car?” is spoken by a character waking up from a big night out. In “baseketball” (1998), the creators of “South Park”, Trey Parker and Matt Stone, play Coop and Remer, two friends having an argument:

COOP : Dude, I’m not gonna cave in! End of story, Dude!

REMER : Dude?

COOP : Dude!

REMER : Dude!

COOP : Dude.

REMER : Dude!

COOP : DUDE!

REMER : Dude!... (Coop opens his mouth but says

nothing. Remer continues, firmly) Dude.

COOP : I guess you got a point there.

Also in 1998, “The Big Lebowski” gave us the most lovable dude yet: Jeff Lebowski, the role that relaunched Jeff Bridges’ career. “The Dude”, as everyone calls the stoner Lebowski, is being lectured by a rich old man of the same name. The Dude finally snaps:

I am not “Mr Lebowski”. You’re Mr Lebowski. I’m the Dude. So that's what you call me. You know, that or, uh, His Dudeness, or uh, Duder, or El Duderino if you're not into the whole brevity thing.

With his bathrobe and his milk-soaked moustache, the Dude had come a long way from the east-coast dandy of the 1880s.

Now the vocative “Dude!” is mainstream—and no longer just for dudes. Young “dudettes”, as women could once be called, routinely call each other “dude”. And even married couples do it. The first time I heard it leap the gender divide, it was startling; now I find it sweet, somehow even more intimate than “baby”, showing the couple as friends, not just lovers. My wife and I never made a decision to be “dude” to each other, it just fills in the cracks in domestic life: “Dude, you have got to stop leaving the closet light on…”

I knew its journey was complete when my 11-year-old son was trying to grab my attention the other day. “Dude!” he said, as I flailed away at one of his video games, “you’re doing it wrong.”

At first I wanted to say, “I’m not a dude. I’m your dad.” But something stopped me. Dude is now all about solidarity. My son just called me “dude!” It was about the nicest thing he could have said.