A luxury of peace and prosperity: Last year, editors at the Oxford English Dictionary, in the midst of a long march toward a third edition, set out to add an entry on “tandem surfing.” (“The practice of two people riding a single surfboard at the same time.”) They were seeking an earlier citation; the best they had was from 1961, in the Los Angeles Times. A researcher contacted a surf museum in San Clemente, California, and eventually wound up in touch with an autodidact in Seattle named Matt Warshaw.

Warshaw is the world’s leading surfing scholar, the Linnaeus of the lineup. Over the years, he has assembled a research library, in his home, of hundreds of books, thousands of periodicals, and some three hundred and fifty movies, and created a database: logged, indexed, searchable. From all this, and from his own experience as a California beach rat, middling pro surfer, and surfing writer, he composed the idiosyncratic yet authoritative “Encyclopedia of Surfing,” which was published, to wide acclaim, in 2003. “I decided to rule this domain that no one gives a shit about,” he said the other day. In the past half-dozen years, he’s been transferring the encyclopedia’s fifteen hundred-odd entries to the Web, and adding many new ones, along with a wealth of photographs and videos. He has likened this migration to Dorothy’s arrival in Oz.

Within a day of the request from Oxford, Warshaw came across, in his stacks, a mention of “tandem surfing” from 1935. You can now find, in the O.E.D.’s Web edition, the following citation: “T. Blake Hawaiian Surfboard (front material, verso of fifth leaf) (caption): ‘A tourist, without surfboard experience, can enjoy . . . tandem surfing. The boy in most cases does most of the work, his partner enjoys the rides.’ ”

The O.E.D. sent Warshaw a few more terms, and before long hired him to be its first-ever Surf Consultant (total pay: four hundred pounds). The O.E.D. has some three hundred consultants, who provide an extra layer of expert scrutiny in such areas of arcana as falconry and wine. It has always tried to keep up with American slang; noted recent additions are “Masshole” and “vape.” “Clearly, they felt they needed to up their surf game,” Warshaw said. He speculated that there was a closet surfer on staff.

The dictionary people sent him about seventy terms, among them “barrel,” “reef rash,” “board sock,” “grom,” “close out,” “dawn patrol,” “doggy door,” “green room,” “shaper,” and “swallowtail.” His database, unfortunately, didn’t contain most of these, so he soon found himself scouring old magazines and manuals—“like a fucking intern.” Days turned into weeks. “I got obsessed,” he said. “I didn’t want to let them down.” Often, he succeeded in finding an earlier mention. Now and then—maybe every third entry—he found something to tweak in the definition, or a bit of illuminating context.

Warshaw is fifty-six. Moving to Seattle from San Francisco, several years ago (his wife works for Amazon), forced him to give up his habit of surfing more or less every day. Also, he’d grown weary of witnessing his own physical decline in the water. “After forty years, I let it go,” he said. “It’s embarrassing. Now I’m a walker. I count steps on my Fitbit.”

His family tree is thick with fancy degrees. “Of course I’m insecure,” he said. “I went to El Camino Junior College, what we used to call ‘thirteenth grade,’ directly out of high school. Fit my surfing schedule.” Just after he turned thirty, he quit his job as the editor of the magazine Surfer and talked his way into U.C. Berkeley. (To commemorate the occasion, his father, a Rand Corporation physicist, bought him a two-volume edition of the O.E.D., which he still keeps at his desk. His O.E.D. surf consultancy, he says, is the accomplishment of his that has most impressed his parents.) He graduated Phi Beta Kappa, with a degree in history, but still has trouble telling nouns from verbs. “I’m like a musician who can’t read music,” he says.

“There’s a built-in sense of irony in surfers’ use of language,” he said. “When we say ‘dude,’ it’s a riff on you thinking we’re stupid.” He was relieved not to have been asked about “sick,” as in “excellent”—“I hate that word”—but, alas, it’s already in there: “Sick, unbelievably good: The Fleetwood Mac concert was sick.”

The O.E.D.’s closet surfer, it turns out, is Warshaw’s handler, the senior editor David Martin, whose phone manner, at least, is low on stoke. “We take the long view,” he said last week. “We track things.”

He went on, “A surf word that we are currently tracking is the verb ‘chandelier.’ It seems to be used with reference to the lip at the opening of a barrelling wave closing in on or falling on top of a surfer.” (One can understand Warshaw’s noun-verb confusion.) Tracking consists of keeping an eye on a term’s usage in books and magazines, and perhaps paying closer attention in the waves off the coast of Wales. Martin also confessed to watching live Webcasts of the World Surf League. “I will note, not when I work,” he said. “It’s a great way to get through a cold and dark English winter.” ♦