Contemplate this, dude: that when I call you dude, there’s a whole range of things I might mean—you’ll understand me from my intonation and the overall context—but each time, I’m also reinforcing a specific kind of social relationship. No matter how I use the word, it always implies the same thing: solidarity without intimacy. It says close, but dude, not too close.

What’s up with that?

Dude may be the most Mandarin Chinese word in American English. In Mandarin, depending on how I intone the single syllable ma, I could be saying “mother” (mā), or I could be saying something as radically distinct as “horse” (mă).

Dude has a comparable quality. Just think of the last time you did something awesome in the presence of a friend who affirmed your awesomeness with the exclamation Duuude! Or the last time you said something objectionable to someone who began setting you straight with a firm and sober Dude. There may not be any obvious difference in denotation between these cases, but the difference in connotation is, you’ll appreciate from experience, pretty major.

So what does the word itself mean? I can tell you what a mother is, and I can tell you what a horse is. But what’s a dude?

Dictionaries struggle with this question. Here, for instance, is Merriam-Webster:

1: a man extremely fastidious in dress and manner: DANDY

2: a city dweller unfamiliar with life on the range; especially: an Easterner in the West

3: FELLOW, GUY—sometimes used informally as a term of address: Dude, what’s up.

Seriously, dudes?

The first two definitions are historically accurate, anyway. (As Richard Hill attests in his study “You’ve Come a Long Way, Dude,” by the latter half of the 19th century, the word was “synonymous with dandy, a term used to designate a sharp dresser in the [U.S.] western territories.”) But they’re also entirely archaic. The contemporary use of dude developed in the Pacific Coast surfing culture of the early 1960s, it entered mainstream popular culture in the early ’80s, and it’s persisted, until recently, along the same basic lines. No, this use has never, as anyone familiar with it knows, translated well as “fellow” or “guy.” But according to Scott F. Kiesling, the author of a seminal 2004 study from the journal American Speech—titled, yes, “Dude”—the term has long implied a particular understanding of fellowship among guys. Its dominant linguistic function, Kiesling argues, has been to enable men, mainly young men, to address one another in a conspicuously straight mode of laid-back camaraderie: “Dude allows men to create a stance … of closeness with other men (satisfying masculine solidarity) that also maintains a casual … distance (thus satisfying heterosexism).” And yet women now use the word, too—both with men and with other women. Perhaps unsurprisingly, usage patterns vary by gender: Kiesling’s work indicates, for instance, that women show a relative tendency to deploy the term when trying to mitigate conflict with friends or acquaintances. (“Dude, you know I’d never do that.”) But even this usage is a variation on a theme. You can, after all, take the masculinity out of dude, and it still works as a way of establishing solidarity without intimacy. If that makes you wonder whether you can take the heterosexuality out as well, consider Bret Easton Ellis. Recently, on Out.com, the (gay) novelist lit into the entertainment industry for, among other condescensions, chronically portraying gay men as “bitchy clowns or the queeny best friend.” How did Ellis describe the kind of chill, unself-consciously gay character he’d like to see more of—the “not-famous, slobby, somewhat lazy” guy who “just wants to be himself”? The gay dude. “Why,” Ellis asked, “isn’t the gay dude I have always known and the gay dude I have always wanted to be not front and center?” It may be one of those rhetorical questions time dispenses with. Dude abides, but it also evolves.