Greetings, trolls of Reddit! Tell me: What’s a troll?

“Memester that hates normies,” says suicideposter.

“Someone who only interacts for reactions,” says _logic_victim.

“Lives under a bridge, votes Republican,” says TW1971. (“no u,” replies Popcap101z, taking the bait, baiting the hook, or both. I can’t be sure.)

“I prefer not to apply labels to myself,” says MyFriend_BobSacamano. (Lulz.)

Asking a troll to define trolling is a bit like asking a terrorist to define terrorism. The question backfires; it invites prevarication and propaganda. But in the past few years, an answer has become increasingly necessary—and elusive. Without one, can we clearly distinguish teasing from hate speech?

If trolls are good at anything, it’s reflecting a culture’s contentions and confusions back at it. Even in those few Reddit replies, the major themes emerge: Trolls traffic in memes, slang, and other in-jokes; they bring internetty “irony” to mainstream politics; they game the attention economy; they weaponize dog whistles and identity politics. Most of all, they’re cacophony with quirky usernames.

Emma Grey Ellis covers memes, trolls, and other elements of internet culture for WIRED.

And yet, knowing all that, I still find “trolls” near impossible to sum up—and I’ve spent much of my career troll-spotting. Story to story, the word has rarely meant exactly the same thing. Trolls can be white male misogynists leaking celebrity nudes, and they can be teenage girls who really, really like Nicki Minaj and will subtweet you into algorithmic oblivion if you disagree. They can also be “virtuous trolls” making once-hateful corners of the internet hostile only to the haters. “Troll” is less umbrella term than a semantic carnival tent, capacious and many-roomed.

Inside my brain (and in WIRED’s newsroom), when and where and why to use the word “troll” has become a point of agita, visited and revisited with each turn of the news cycle. So I found it interesting, and a little alarming, when Robert Mueller offered up his own definition last week: Trolls are “internet users—in this context, paid operatives—who post inflammatory or otherwise disruptive content on social media or other websites.” It’s a footnote on an otherwise totally redacted page of his report on Russian influence in the 2016 election. (It seems safe to assume the context is the Internet Research Agency, a Kremlin-linked organization sometimes referred to as a “Russian troll farm.”) His definition takes an admirable stab at corralling a feral idea—in a hopelessly outdated way.

Maybe it was true in the 1980s. During the internet’s infancy, users workshopped bothersome practical jokes like “scrolling”—the Rickroll of its day. Others specialized in needling forums into no-winner arguments. They did shape other’s online behavior, giving us internet adages like “Don’t feed the trolls,” but mostly they were pests. For many people—those who have never been trolled, who tend to be men and are most often white—this notion of trolling persists unchallenged to the present day, creating the crisis of language in which we find ourselves. As Ginger Gorman, an Australian journalist and author of the new book Troll Hunting, puts it: “Understanding lags far behind the actual practices of trolling.”

This much is known: The lulzy basement dwellers of old aren’t the same people terrorizing the internet today, and they haven’t been at least since Gamergate. Being a jerk on the internet takes time and energy, which means that many soldiers of early-aughts “flame wars” have since gotten jobs and families, aging them out of the culture. According to Whitney Phillips, author of This Is Why We Can’t Have Nice Things, Gamergate intensified trollish sites like 4chan. “As the site became more radical, those who didn't like that shift quietly turned away,” she says. “Others who connected with misogynist and other bigoted messages restocked the participant pool.” Extremism is contagious: Anyone who lingered would have also been hardened, or even radicalized.